armillaria caligata: fungus with a brown cap and white gills and a membranous ring halfway up the stalk
agaric: a saprophytic fungus of the order Agaricales having an umbrellalike cap with gills on the underside
umbrella plant: rhizomatous perennial herb with large dramatic peltate leaves and white to bright pink flowers in round heads on leafless stems; colonizes stream banks in the Sierra Nevada in California