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.
A really good one. Indoor fungiculture can be a lot easier than horticulture with cheaper inputs.