These interesting galls were found by Jane Gowery on the flowering male catkins (or "aments") of a Canyon Oak (Quercus chrysolepis).

The overall impression was of more-or-less linearly arrayed strings of tightly and irregularly appressed individual, globular, larval gall chambers, each 3-5mm in diameter, with a greenish-yellow surface that was densely covered with long, glisteny-white woolly hairs. It appears each globular chamber was an outgrowth from a single staminate flower...with the orange, linear objects plastered against the white woolly tufts being the anthers of the original flowers.

Among current BugGuide posts, the closest match I could find was the eastern species Callirhytis quercusoperator, originally described in 1862 as Cynips quercus operator by Osten Sacken here, and fleshed out in more detail under the name Andricus operator in Kinsey(1922). Alternatively, working through Felt's 1917 "Key to American Insect Galls" led to Andricus turneri, which I'm presuming is synonymous with Callirhytis turneri, listed near C. operator in Felt(1)(1940).

But from size and host species (among other things), the gall in my post here doesn't seem to fit with either of the above candidates. Instead, is appears to correspond to the flower gall illustrated in Weld(2)(1957) as Fig. 50 and listed there as an unreared and unnamed species growing on Q. chrysolepis and having "woolly galls along the staminate axis".