The rise of farmers’ markets — in city centers, college towns, and rural squares — is testament to a dramatic shift in American tastes. Consumers increasingly are seeking out the flavors of fresh, vine-ripened foods grown on local farms rather than those trucked to supermarkets from faraway lands. “This is not a fringe foodie culture,” says [Anthony] Flaccavento. “These are ordinary, middle-income folks who have become really engaged in food and really care about where their food comes from.