I eat stinging nettles, lambs quarters and several varieties of flowers. I know that cattails are completly edible, chickory roots are a coffee sub, part of milkweed is edible (can't remember exactly what right now), Queen anns lace roots can be eaten, burdock root is edible.

There are some books on wild edibles available. Start with your library.

I have a book on edible garden weeds in Ontario. The book has recipes and the aim is to try them all this summer. So far I have eaten sow thistles(they are much like spinach (cooked) but a little bitter)and Comfrey leaves and stems (fairly bland but ok). Burdock roots (Gobo)and cattail /bulrushes are next.
Josie23 - The half grown milk weed pods are edible according to my book. They're on for later this summer.