A couple of years ago I started buying one of each of the very expensive mushrooms like Reiki or Portobellos, harvesting the spores and letting them go to town in rich compost. The plant itself is actually the stringy rhizomes underground; whereas the mushrooms are disposable fruiting bodies that can be picked and picked and will still come back. They are fantastically flavorful, and don't need light. Not many calories, but interestingly they do provide vitamin D which may be hard to come by in landlocked areas. Just don't go larking about picking wild mushrooms unless you are very savvy about which ones are poisonous. I bent that rule only once, earlier this year, when I found an unexpected small gold mine of morels growing in our front yard. There are no poisonous ones which resemble them and so after scrutinizing the photos repeatedly I decided it was safe.
I now have them in flats in my closet. Simple mushroom flats: wooden crates lined with window screening or hardware cloth and filled with a mixture of soil and compost. The spores of mushrooms are virtually too tiny to see easily and actually escape constantly from the mushroom's gill surface. I have read of wild harvesters who recommend carrying the ones you have picked in mesh bags so that as you walk, spores drift downwards to propagate new supplies. You can shake whole mushrooms over your culture medium. You can also cut out the gills and let them roll around gently in the medium. One thing that should be mentioned, and I didn't do so before, is that your culture might contain fungal spores of its own. These can be eradicated by sterilizing the medium, either with heat or with ethylene dioxide gas, which is sold at many nurseries.
Offered by Jenny.
My wife, who is a vegetarian, is also pretty excited about the fact that some mushrooms (at least Shiitake) contain a complete protein like meats. There are different classifications of mushrooms that attack the rotting things at different stages during their decay. Some, like Shiitake, are aggressive rotters and need recently cut (at least 2 months, but not starting to decay) hardwood stumps or branches while others thrive in a decaying material, like Portabella and white buttons.
Offered by John.
Spore Prints. These will last a long, long time. Just need the medium to grow them in.
Offered by Bruce.