Mushrooms in The Garden by Hellmut Steinbeck lists a few pages of mushroom species that can be cultivated. Whether you purchase spawn or make your own, the next step is to inoculate the final substrate that will eventually produce mushrooms. The main thing to remember is that you want to introduce your fungus into a medium that is relatively free of other fungi. If you are growing on logs or stumps, these must be freshly cut, preferably winter cut so that the sugar content in the wood is high, giving an initial boost to the mycelium. Simply sterilization, means steam sterilization in an autoclave at 15 psi for a few hours or at atmospheric pressure for at least 12 hrs.
Pasteurization means boiling the medium in water.
Almost any type of hardwood logs can be used for mushrooms. Commercially the most common species grown on logs is shiitake. This is due to the fact that log cultivation is usually more expensive than sawdust cultivation and shiitake give a higher financial return than other types of mushrooms. Also for commercial cultivation oak is the preferred hardwood because it has a longer bark retention period than other species such as maple, alder, beech etc. The bark keeps the moisture in the log and keeps out competitor fungi.