On Tucson’s south side, on the corner Third Avenue and 25th Street, sits a little shack with a roof of solar panels. At the front, behind its chain link fence, a fading hand-painted picture of La Virgen de Guadalupe greets all who approach. It’s Saturday, and Casa Maria welcomes anyone in need of a meal.

Outside, volunteers form themselves into a human assembly line: a church volunteer with graying hair, a University of Arizona student and locals from the barrio, some sporting baseball caps, others cowboy hats. They begin to unload box after box of donated food — tomatoes, a battered box of lettuce, apples that didn’t sell — days-old produce that typically goes to the garbage.