Mushrooms are the most wondrous inventions of the last billion years of evolutionary history on earth. Their overnight appearance is a pneumatic process, with the inflation of millions of preformed cells extending the stem, pushing earth aside, and unfolding a cap above the dewy grass. Once exposed, a mushroom's gills shed an astonishing 30,000 spores per second, delivering billions of microscopic particles into the air in a single day, cells that may be capable of spawning the largest organisms on the planet. Mushroom colonies burrow through soil and rotting wood. Some hook into the roots of forest trees and engage in mutually supportive symbioses; others are pathogens that decorate their food sources with hardened hooves and fleshy shelves. Among the staggering diversity of mushroom-forming fungi we find stranger apparitions including gigantic puffballs, phallic eruptions with revolting aromas, and tiny “bird's nests” whose spore-filled eggs are splashed out by raindrops. But it is the poisonous effects of a handful of fungal metabolites, and the powerful hallucinogenic qualities of others, which account for the central place of mushrooms in mythology and their commonest associations in Western culture. This book explains what mushrooms are (Chapter 1), how they work (Chapter 2), and what their underlying colonies do (Chapter 3); the harvesting and conservation of wild mushrooms and the cultivation of domesticated species are addressed in Chapters 4 and 5, the science of poisonous and hallucinatory fungi in Chapters 6 and 7, and deceptive claims about medicinal mushrooms in Chapter 8.