From Michael Pollan to locavores, Whole Foods to farmers' markets, today cooks and foodies alike are paying more attention than ever before to the history of the food they bring into their kitchens--and especially to vegetables. Whether it's an heirloom tomato, curled cabbage, or succulent squash, from a farmers' market or a backyard plot, the humble vegetable offers more than just nutrition--it also represents a link with long tradition of farming...