There are many different forms of mushroom spawn as well as many different varieties that can be grown at home. Some mushroom spores are sold as plugs (the spores have been impregnated onto small dowels of wood) and these are used to grow mushrooms on logs. The most popular form of mushroom spawn is rye grain spawn, which is simply rye grain with the spores mixed together. You can also grow mushrooms from a spore-print, but this is a more complicated method as you have to grow them on a material like agar on a petri-dish and then transfer it to another suitable substrate.
These “mushroom patches” are mushroom spores mixed with grain that is used in beds in the garden. You simply select a suitable location, sprinkle the spawn over the chosen patch, and then water it according to the instructions. Not many mushrooms can be grown like this outdoors, but it is well worth giving it a go.