Mushrooms, a kind of fungus, come in many varieties. From those on a pizza to those in spaghetti sauce, mushrooms enhance our cuisine and flavor our lives. But not all mushrooms are so harmless. Some contain toxic and/or hallucinogenic compounds. Hallucinogens are substances that alter or produce false perceptions of sight, sound, taste, smell or touch. Some toxic substances in mushrooms can cause severe illness and even death.