Although Felt said these seeds (or achenes) "were unmodified externally" the galls being tentatively identified on iNaturalist as A. adenostoma galls very definitely modify the seeds. The larvae in the modified seeds have been confirmed as Asphondylia. Once pupae are found or raised and sent to Ray Gagne, the working assumption that these are A. adenostoma galls can be confirmed--or possibly refuted.

See comments, particularly those of Joyce G[ross], who sent photos to Ray Gagne, here and here.