I found this website on Texas wild edibles. I like it for the way it has different ways of looking up plants:
Find by Environment
Find by Season
Find by Use
My favorite serach is by Habitat, He even has, by what will be growing in your yard! Even though the site is Texas focused; I think the site is very well put together and I think the site could be used universally.
Next I found a great android app.
Wild Edibles by "Wildman Steve Brill"
Just do a search on google apps for wild edibles.
I've been coming along on recognizing edibles; I just saw some goldenrod on the way home, I now know what those miserable weeds are in my yard that I keep finding with my bare feet, SOW THISTLE.
Well, I hope this helps others in thier perpreation for the Zombie Apocolypse!