This is an interesting article from Frontier freedom on making lye soap. I have seen recipe for making lye soap but this one is different because before you get to the making soap part they teach you how to make the lye from wood ash.
I'd still be afraid to collect mushrooms myself: Edible fungi chart. If the world is ever covered in darkness, the only plants that will grow without sunlight are mushrooms. Stick this in your survival guide!
10 common weeds that you find in your yard and how they can heal sicknesses, burns, sores and other ailments. - After checking this list, I've got SIX them growing around my yard and garden. It's nice to put a name to the plants.