Northwest Foraging written by Doug Benoliel in 1974 is what made me decide that Seattle was an okay place to live. Most foraging books focus more on the East coast and I was getting worried that there wasn't anything interesting out here. Northwest Foraging is one of those excellent gems of a book that just opens new doors. It's clear from reading the book that Doug has tried most if not all the plants listed - including some of the mildly poisonous ones.
The physical descriptions of the plants are generally brief, but complete and in conjunction with the excellent line drawings are enough to be reasonably confident you've got the right plant.
Where this book really shines however is it's description of the edibility of each plant. Not only does it state what is edible and how, but he goes into detail about what is worth collecting and what you might find the tastiest. As if this weren't enough he includes recipes at the end of the book, though I have to confess I haven't yet tried any of them.
All in all an excellent book which should be welcome on any bookshelf in the north west.