PITTSBURGH — For years, Barbara Johnstone, a professor of linguistics at Carnegie Mellon University here, bought shares in a C.S.A. — a community-supported agriculture program — and picked up her occasional bags of tubers or tomatoes or whatever the member farms were harvesting.
Her farm shares eventually lapsed. (“Too much kale,” she said.) But on a recent summer evening, she showed up at a C.S.A. pickup location downtown and walked out carrying a brown paper bag filled with a completely different kind of produce. It was no good for eating, but it was just as homegrown and sustainable as what she used to get: contemporary art, fresh out of local studios.