Various species grow on hard or soft wood logs. If you have access to fresh logs, this is a great way of turning dead space into a garden. These will produce 1-3lbs of shiitake per log per year. I got them for free when a redditor was cutting down a tree on their farm so it can be very low-cost high-yield.
If you have a good drill bit and unseasoned hardwood logs, it's very easy. Drill, insert the inoculated dowels from r/mycobazaar, cap the holes with bees wax, soak them for a day, and then you just stack them in the shade and water them every few weeks. 1-3lbs of shiitake per log per year.