I’ve been doing some reading on edibles too.
FWIW, I learned in past couple of days that crabgrass is edible and actually highly nutritious! Also known as Polish Millet - has been cultivated for eons.
http://www.eattheweeds.com/crabgrass-digitaria-sanguinalis-2/
http://en.wikipedia.org/wiki/Digitaria_sanguinalis
I shared that with a person at one of our local stores today, and while we laughed at how ridiculous it might be to have to eat crabgrass since our society is working so hard to get rid of it, I nevertheless saw the wheels turn. Maybe that is one neighbor who won’t starve now if things get dire.
I also told her that maple seeds are edible as well. That made sense to her, because of the ability to get maple sap and turn it into syrup.