Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Psilocybin-containing mushrooms, also known as shrooms and psychedelic or magic mushrooms, are fungi that contain a hallucinogenic substance. Used already by ancient civilizations in order to inspire religious or mystical experiences, magic mushrooms are known for their mind-altering effects. However, active ingredients of psychedelic mushrooms have medical value as well. Learn more about psilocybin-containing mushrooms, their history and effects in this book.