Grow mushrooms on your kitchen counter, or create a growing environment.
These blocks are made with woodchips and other ingredients to create a viable substrate. The substrate is stuffed into a biodegradable bag, formed into a block, heat-sterilized, inoculated with the mushroom strain of choice, and heat sealed to prevent contamination.
The bags have a micro-pore patch to allow the mycelium to breathe as it grows through the substrate. Once the mycelium is fully developed, open the bag to allow the mushrooms to grow out of it.  (follow instructions specific to each strain).