Edible and Medicinal Plants of the West [Paperback]
Gregory L. Tilford (Author)
Has photographs instead of illustrations, which I like. Also sometimes will tell you how to eat it. But there really aren't that many plants in the book that are actually edible.
Another really good one is Mushrooms Demystified. You probably didn't want to try mushrooms, but it's a really good book anyway in case you are a collector of field guides. Witty, funny and beautiful pictures and uses a keying system for identification.