It is 2 -- 5 cm. in diameter, and is strongly folded, somewhat like the folds of a brain (gyrose).    From Wordnik.com.  [Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.] Reference

Hymenium covering the entire free surface or confined to one portion; smooth, gyrose, folded or lobed; or hymenium lamellate, porous, reticulate or toothed forms which are gelatinous and provided with continuous basidia may be sought here.    From Wordnik.com.  [Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.] Reference