One person’s trash is another’s treasure.

It’s 9:30 pm on a Tuesday outside an undisclosed supermarket on the border of Sutton Place, where a group of 10-15 “Freegans” has gathered for a biweekly “trash tour” to dumpster dive for salvageable food and other goods.

Clad in masks and gloves, these urban foragers — who encompass multiple boroughs, vocations and age ranges from 20s to 60s — scavenge the cans in hopes of getting their landfill.

A far cry from the Matterhorns of putrid refuse depicted in movies, these trash bins harbor a treasure trove of items seemingly ripped from an NYC boutique supermarket aisle — because they were not too long ago.

One dumpster diver salvages immaculate packages of organic guacamole.

Another garbage gourmand rescues loaves of unblemished sliced bread.

Others scour grocery-grade packets of salmon, a farmer’s market’s worth of produce, and several quarts of heavy cream that can retail for up to $10 a pop.

Expedition leader Janet Kalish, 63, even lamented, “I’m sure I missed a lot and eggs and mushrooms.”

“I got a bunch of blood oranges here,” added Cindy Rosin, who advised garbage gatherers to sniff the perishables upon opening to ensure they’re safe to eat.

Despite dumpster diving being somewhat of a normalized practice, the savvy scavengers refused to disclose details about their lives, including what they do for a living — or if they even work at all.

These “canned good collectors” work fast, given the brief window between when the trash is put out from the fancy supermarkets and when it is picked up. On the plus side, this increases the likelihood that their bin banquet is fresh.

“Stores might put it out at 9:00 p.m. for the trucks to come at 11:00,” Kalish, who has memorized the pickup times at her various dumpster diving hotspots, told The Post. “It’s not like it’s sitting there wafting odors.”

She added that even between 9:30 and 10 p.m. on a “sweltering” summer night, people can grab the yogurts and feel that they’re “still cold.”

Kalish has dedicated her life to spreading the message of the NYC Freegans, a grassroots organization whose members seek to minimize waste by recovering and redistributing discarded goods.

They spread the gospel via free “trash tours” that people can sign up for on Meetup and encompass nearly every borough save for the Bronx and Staten Island.

Dive spots are selected through trial and error based on factors such as location, trash accessibility, and the quality and variety of the discarded goods, with larger supermarkets proving especially fruitful.

However, the Freegans never lead tours in the same place twice to avoid encroaching upon “people who rely on this food as their sustenance,” according to Kalish, who dives solo as well.

Fortunately, anyone can become a Freegan, she declared. “It’s not like we have a set of rules and a strict kind of authority to tell people you are and you aren’t,” the dumpster dive instructor explained to The Post. “If somebody wants to call themselves a freegan, then welcome to the world.”

Rooting around in the trash isn’t the sole aspect either, as they also host complimentary craft salons focused on repurposing discarded materials into art, and free communal feasts where dumpster divers enjoy the fruits of their labors.

A former teacher for 29 years, Kalish attended her first Freegan meetup in 2004 after hearing that people were saving big by finding free food. Initially skeptical, the dumpster dive instructor was hooked after joining a trash tour.

Now, Kalish estimates that she was able to retire early without suffering “financial hardship” in part because she supplements over 90% of her diet with salvaged goods.

“I don’t spend much money,” Kalish told The Post. “My food comes free.”

And the leader of the Free-gan world is not the only one who’s jumped on the canned wagon. Once a taboo pastime, trash-to-table dining has never been trendier, thanks in part to the rise of “dumpster diving” bin-fluencers.

Anna Sacks, aka “The Trashwalker,” has amassed over half a million Instagram followers with viral videos that show her intercepting a cornucopia of junked gems.

In one of her most popular clips with over 5 million views, the trash-tivist exhumes a Halloween haul’s worth of Twix, Snickers and other candy bars from a CVS bin.

Another shows her scoring a Hurom H-AA Rose Gold Slow juicer and accessories that retailed for nearly $500.

The dumpster diving craze couldn’t have come at a better time.

US consumers are struggling with stubbornly high food costs as grocery prices rose 2.9% in April alone compared to last year due to an inflation spike fueled by the Iran war.

Kalish exclaimed that many people practice Freeganism as a “viable way to save themselves from debt” and “to survive in New York City.”

Along with scoring complimentary essentials, dumpster divers also strive to expose corporations’ so-called decadent excesses in the hopes that more edible goods are redirected to those in need.

According to RTS.com, the US wastes around 120 billion pounds of food — more than any other country — accounting for around 40% of the global food supply.

“The food is thrown out because our system is flawed and it’s inherent in our system to waste this kind of food, this quantity,” the trash-tivist told The Post while bemoaning the surplus. “And this is just one store on one night and if you think of all of the thousands of stores in the city and how much is getting wasted, not just this city, but this country.”

The retrieval expert explained that fresh inventory will often get bumped simply because stores need shelf space.

“They’re stocking their belts with the new ones so whatever fits on the shelf gets put there and ones will get taken off, not because they’re bad, but because they just got to restock it,” she said. 

And it’s not just the bare necessities that get discarded.

Gil, an environmental educator, told The Post that he rescued six imported cheese wheels worth roughly $450 apiece from a “cold storage facility.”

“I had Ikea bags [of the stuff],” recounted the repast recycler, who generally dives solo but came along for the ride.

When Gil first moved to the city in 2010, an “elder” showed him an area outside an industrial bakery in Long Island City that supplies luxury hotels. He said it housed “three dumpsters of really high-quality artisanal bread.”

“If you go early in the morning, it’s still warm. It’s fresh,” he explained. “They bake for the maximum order that they could possibly get for a day and everything that they don’t get ordered, they just roll it.”

“You can have a whole luxury lifestyle living out of a dumpster,” Gil declared. “You just have to have to drop your ego and dive in the dumpsters.

Along with haute cuisine, many can score expensive electronics, with Kalish recalling finding a mint-condition laptop and accessories during one dorm dive. 

Despite these upmarket hauls, many people are reluctant to embrace Freeganism. Kalish explained that many people are predisposed to think that anything that comes from the garbage is inherently “dirty.”

Some of the concerns are valid — nobody wants food poisoning from a dubious salmon filet — but the seasoned rummager believes that many of the fears are overblown.

“I’m not just recklessly eating things even though they’re expired,” said Kalish, noting that people can spot mold, smell when food has gone bad and check dates.

If meat is mixed in with fruit, she’s “less inclined” to take it.

Thankfully, few dumpster divers claim to suffer adverse effects from dumpster dining. As Cooper Union grad Violet Caleca put it so succinctly during the tour, “I’ve eaten trash bagels for five years and I haven’t gotten sick.”

Thankfully, dumpster diving is generally legal in NYC — hence why they’re allowed to lead public trash tours — provided participants don’t trespass in fenced areas, which are generally more common elsewhere anyway.

The bigger concern, Rosin said, is that store managers will be ticketed or fined because divers leave a mess behind. “If people are tearing bags open and stuff, then they come out and get mad,” she said.

That’s why the Freegans take pains to “open [the bag] at the knot,” tie everything back up and “leave it cleaner than we found it,” Kalish explained.

Ultimately, she believes the best way to earn converts is by having them see it for themselves.

During the tour, several curious college students who had initially been watching from the sidelines eventually joined in, filling bags with flowers and fresh fruit that would’ve otherwise ended up at a landfill.

“[Spectators] often stop and say ‘what is this? Can I have some?” Kalish said.