The cultivated mushroom (Agaricus bisporus) is the world's most widely grown edible fungus — sold as the pale "white button," the browner "cremini" and the fully grown "portobello," all the same species at different ages. Mild, meaty and deeply savoury, it is the workhorse mushroom of the kitchen, prized for an earthy aroma and a near-meaty depth of umami.