Feron californicum (Hymenoptera: Cynipidae)
Pacific Crest Trail, south of Hwy 74, east of Anza, San Bernardino National Forest, Riverside County, California
May 19, 2022

Wasp gall on Quercus cornelius-mulleri. Beutenmuller's 1911 species description fits Trichoteras californicum well in terms of the gall. There is also a chance this could be a different (but undescribed) species.