I've been reading a lot about sustainable agriculture and food recently, and one of the most interesting projects I've come across is Gary Paul Nabhan's RAFT: Restoring America's Food Traditions, which works along with the SeedSavers Alliance and Slow Food's Ark of Taste, to identify and bring back indigenous foods. (Nabhan recorded his own experiences in this area in his book Coming Home to Eat).
RAFT's work is informed by a bioregional vision of what constitute's local food--what they call "place-based food traditions." It gives a quite interesting picture of what North America would look like from an indigenous-diet perspective. (The recently published book adds a "Crabcake nation" on the East Coast down from the Chesapeake.)