The Dumpster divers started their bicycle run just after nightfall on a summer Friday, rolling through the steamy streets of Williamsburg and Greenpoint, stopping only to dig through trash bags and pull out produce. They wore plastic gloves for the messier bags and used a flashlight on the darker stretches of sidewalk. Then they loaded their finds onto a cargo bike, retied the bags and cycled on.

The goal was to find enough food to supply an every-other-week gathering called Grub, which one founder has described as “a cheap, simple dinner for friends and co-conspirators.” It is a communal meal created from food that would otherwise have been wasted — and that many people might not deign to eat.

So Jessie Martens grabbed a bruised cantaloupe and some shiny heirloom tomatoes from a curb in front of a supermarket on Union Avenue. Eric Levinson found bottles of organic juice being discarded outside a building near the Pulaski Bridge. And on Bedford Avenue, Phoebe Gray and Eric Lewis sifted through seven bags of trash before uncovering a bounty of kale, blackberries and peppers, as well as a punctured avocado that Mr. Lewis called “premade guacamole.”

“It’s a way to feed a lot of people for free,” Mr. Levinson, a 27-year-old chef and yoga teacher, who was piloting the cargo bike, said of the group’s scavenging. “And it’s a way to raise awareness of the way food is wasted.”