The Garden of Eaden: HOW TO GROW MUSHROOMS AT HOME. ---- These are button mushrooms, which grow on compost. Compost. Mushroom Compost is made from a mix of well rotted materials such as hay, straw, straw horse bedding, poultry litter, cottonseed meal, cocoa shells and gypsum. Sphagnum moss peat is then added to this so as to provide a consistent product. Be in mind that it may well be easier to buy some pre-made!