check out the mushroom gallery
If you have someone along with you who recognises the edible mushrooms in the wild, than go for it, after cooking them. If not, do not try it. I find mushrooms all the time.
Somethings that actually are good to eat have close cousins that may frighten you away. One of these is Sumac. Poison sumac is something that should be avoided, but the larger bush or tree sumac provides a fuzzy berry that is used in middle eastern spicing, and can make a very lemony tea.
Sumac grows along highways, in feilds that have gone fallow for a few years and likes partial to full sun. The dried berries in the spring can be soaked for a lemon flavored tea, or crushed to be added to food. The fresher berries can just be pressed or squeezed for the juice or used for cooking, like for stuffing a fish.