omphalia

from The Century Dictionary.

• noun A genus of white-spored agarics having a cartilaginous stem broadened at the apex and gills decurrent. The pileus is somewhat membranaceous. The species are numerous, widely distributed, inodorous, and none are known to be edible. O. campanella is a common species on decaying trunks of coniferous trees and O. umbilicata in woods among moss.