I just pulled 4 beautiful Garden Giants from near my compost pile. They started off on a dark, wood chips and cardboard area near by and have wandered a bit. I started with a kit because I wanted to be familiar with the shape, smell, etc. of the mushroom since we have wild ones here that are poisonous. I also chose a mushroom that doesn't look like the normal ones here, so there would be no mistake. I hear a lot of people have luck with the garden giant in their garden coexisting with plants. My experience so far seems to speak to that, though I'm no expert. It isn't in the compost pile, though this type I think likes compost. I see there being three general categories of mushrooms: hardwood lovers, softwood lovers, and compost lovers. Most all will grow a little on cardboard. Softwood lovers do amazing on cardboard and people also use grain or often straw with them. In other words the medium depends on the mushroom. A good starter mushroom for me was some oyster mushrooms mycelium grown from store-bought mushrooms on cardboard. It was free and allowed me to experiment and become familiar with fungi. Good luck!