Spots 
Mushroom development starts underground as a network of fine white threads known as mycelium. Small knob-like buttons emerge along these strands, containing the fully formed cap and stem in miniature. As water expands the tissue, the stem elongates rapidly and breaks through the universal veil, exposing the gills beneath. Spores drop from these gills to propagate new mycelial networks in the surrounding soil.
The Agaricaceae family is distinguished by radiating vertical plates called gills beneath the cap. Spores form on specialized cells along these gill surfaces and drop away into air currents when mature. Identification relies on spore color, which is determined by leaving a fresh cap on paper to produce a spore print. Gills may attach directly to the stem, run down it, or remain completely free.
The genus Amanita includes the most deadly mushrooms, characterized by a cup-like volva at the stem base and a ring on the upper stem. These structures remain from the universal and partial veils that protected the young button. White spores and free gills further mark the genus, separating it from edible lookalikes. Identification requires excavating the complete base to verify whether a volva is present in the soil.
Members of the genus Lepiota feature white spores and gills that do not touch the stem. The stem ring in mature specimens often breaks free from the stalk, sliding up and down like a loose collar. Unlike Amanita, Lepiota species lack a basal cup or volva at the root. Scaly patterns frequently coat the upper surface of the cap as the outer skin cracks during expansion.
A botanical guide to identifying, understanding, and distinguishing edible and poisonous American mushrooms by structural features.