Mushrooms and Manure
Manure is organic matter, which can be used as organic fertilizer in agriculture. It is mostly derived from animal feces and has been used for centuries as it provides many benefits. Adding organic matter to soil improves soil structure, increases the water-holding capacity, improves drainage, provides a source of micronutrients, reduces wind and water erosion and promotes growth of worms and other beneficial soil organisms.
Mushrooms and Manure
Contrary to popular belief, mushrooms are not grown in animal poop. Many edible Mushrooms are grown on a pasteurized substrate that contains composted manure, along with different organic materials such as straw or rye, and gypsum to manage the ph. (See Bulk Substrate).
If you want to grow mushrooms, you can prepare the substrate yourself, or buy it ready to use, for example at here.