I recently finished a History Channel documentary on the history of food.
Several reference books were helpful throughout the process.  "The Food
Chronology" by James Trager is just what it sounds like--a breakdown by year
of most of the foods you can imagine with brief histories.  John Mariani's
"Dictionary of American Food and Drink" is also good for history and tidbits.
On the weightier side, Waverly Root has a pretty definitive history (although
not always reference friendly) called "Eating in America."  Good luck....

Scott Tiffany