puffball or smokeball, fungus in which the aboveground portion is typically a stemless brownish sac with an opening at the top through which issues the dustlike mass of ripe spores. The common puffball is Lycoperdon gemmatum. The giant puffball ( L. giganteum ) may reach a diameter of 1 ft (30 cm) or more. No puffballs are poisonous, and most forms are edible when young. They are related to the mushroom and are similar in flavor. Puffballs are classified in the kingdom Fungi, phylum (division) Basidiomycota.