Hello,
Unless you know what you are doing, i would suggest you to
NOT randomly pick and eat mushroom. This can get you sick and even kill you if you pick up the wrong mushrooms. Be sure to have a mushroom book and know what you are looking for. Yes mushroom (magical) are known to grow into cow poo but not only those does.
You should consider growing you re own if you are into mushrooms to avoid getting bad batch from any dealer or picking bad mushroom.
You will get all information you need on this forum;
http://www.shroomery.org/