By far the best site on the internet for information about foraging from your yard is Eat The Weeds.com. It is the site of Green Deane.
There is a forum there that has helped me over the last couple of years to identify many "weeds" from the yard. It turns out that many, many things are edible.
Just to name a few: sorrel, begonia, henbit, dandelion, pokeweed.
If it's edible, he's probably done a video on it!