Fig. 192. Agaricus campestris.

A. Agaricus campestris. a. Button. b. Ditto; the annulus splitting from the pileus.
B. A. campestris (flap or full grown mushroom.
C. A. Georgii.

This image is from Mushroom in Pereira's Elements of Materia Medica and Therapeutics, 1854.