It has a rusty orange spore print and a bitter taste and contains the psychedelic chemical psilocybin.

The specific epithet aeruginosus refers to the bluish staining caused by psilocin polymerization.

It is smooth, dry, dusted with rusty orange spores and has a cottony, scanty, yellowish, partially fibrillose veil that leaves an evanescent zone of hairs near the apex of the stipe.

It is colored more or less like the cap; it is flesh whitish, tinged greenish or bluish-green, becoming yellowish or pinkish-brown when dry.

Gymnopilus aeruginosus grows gregariously to cespitosely on stumps, logs, and woodchip mulch/sawdust on hardwood and conifers.

It grows in spring, fall, and winter, and is common in the Pacific Northwest.