Mushrooms are never worth the risk if there is any doubt at all. Even then, it's just added flavor for your real food. Dandelion greens are very good -- add some balsamic vinegar & olive oil and you've got a decent salad. So many people go out of their way to kill dandelions in their lawn, but they're one of the few plants in a lawn that are actually nutritious. Dandelions and clover make for a great lawn