Often mistaken for the better known Marasmius rotula (小白小皮傘), this tiny mushroom differs by growing on fallen oak leaves, rather than sticks and woody debris. Additionally, it has a more rounded cap (Marasmius rotula looks squarish and flat-topped when viewed from the side), and slightly larger spores.
Ecology: Saprobic on the fallen leaves of oaks and other hardwoods (rarely reported on conifer duff); growing alone or, more often, gregariously (dozens may be found on a single leaf); summer and fall.
Cap: 2-15 mm across; convex, but soon with a central depression; pleated; smooth or very finely velvety; dry; whitish or very pale grayish brown.
Gills: Attached to a tiny “collar” that circles the stem; whitish; distant.
Stem: Up to 60 mm long; less than 1 mm thick; equal; dry; shiny; wiry; pale above, dark brown to black below; inserted directly into the leaf.