[2] Growing solitary to gregarious in open areas of conifer/hardwood forests; common under Bishop pine (Pinus muricata) along the coast north of San Francisco; fruiting shortly after the fall rains.

German botanist Paul Kummer erected the genus Clitopilus and gave the miller its current name in 1871.

The cap is initially convex when young, but in maturity flattens out, usually with a shallow central depression; the margin is often inrolled.

The gills are decurrent in attachment to the stipe, spaced together rather closely, and whitish, although they often develop a pinkish hue in age.

[7] The stipe is 2 to 8 cm (3⁄4 to 3+1⁄8 in) long × 4–15 mm thick, and white or sometimes grayish;[8] it may be located off-center or enlarged at the base.

The cucumber odor of this species has been attributed to trans-2-nonenal, which is present at a concentration of 17 μg per gram of crushed tissue.

[9] C. prunulus contains the volatile compound 1-octen-3-ol, making it unpalatable to the coastal Pacific Northwest banana slug, Ariolimax columbianus.