Usually when it comes to growing fungi, it's important to start with the fungus sprouting itself – that's what the mushrooms grow from so it's an important ingredient. Without it, it would be like trying to grow an apple tree without the apple pie – it never goes to work. Usually, the fungus sprout will be specially created by a mycologist, and will usually consist of a kind of grain that has been impregnated with mushroom mycelium (mycelium is what mushrooms come from).
You can create your own mushrooms in several ways, but most people do not realize that you can actually grow your own fungus mushrooms, so you can reuse old mushrooms and start your own cycle with fungus culture.
All you have to do is cut a small portion of the fungal stem, no more than an inch long. It is important to try to use the bottom of the stem, with the bulbous part of the stem intact (this part is traditionally removed before preparing the sponge for cooking and packaging before selling in stores). But if you have already grown some of your own mushrooms from a kind of spawn, then you have no problem keeping the healthiest assortment of rods. You can still try using the strain from shop-made mushrooms, but you can not be very successful.
It is important to say that not all fungi have this stem growth ability and there are only few varieties that are known to be able to recover from their stems. These include oyster mushrooms (Pleutrous Ostreatus), Parasol Mushrooms, Morels, Prince, and many more.
All you have to do is remove a section of the trunks and get some corrugated paper. Soak the cardboard and then try to peel it halfway so the paper is as thin as possible. Then place the board on a surface and place some of the rods on top. Try leaving about 6 inches of cardboard per stem. Cover the stems with the rest of the corrugated cardboard and then enjoy for a few minutes. Place the folded pieces of cardboard in an old box – cardboard, wood or other that keeps the box moist and then put it in a shady position in your garden before you cover it with leaves.
What will happen is that the mycelium begins to grow through pieces of cardboard, from the stem, using the materials in cardboard as food (mushrooms grow naturally on wood and so cardboard is ideal to use and easier to break down). After a few months you will have your own cardboard spade and you can either use this to grow more mushrooms or mix this cardboard pad with straw, create an outdoor bed or mushroom patch or try to transfer sprouts to other substrates.