any of various round basidiomycetous fungi (esp. order Lycoperdales) that burst at the touch, when mature, and discharge a brown powder
See puffball in American Heritage Dictionary 4
noun
Any of various fungi of the genus Lycoperdon and related genera, having a ball-shaped fruiting body that when pressed or struck releases the enclosed spores in puffs of dust.
Informal The rounded head of a dandelion that has gone to seed.