Pteridaceae, Polypodiales.
Only species of Pellaea in Anza Borrego other than P. andromedifolia
See follow-up 12 years later, in which this bush still looks glorious:
Also see Don's closeup view:
https://www.inaturalist.org/observations/208041693
for which he paid the heavy price of getting grass stickers in his socks.
The same bush has been putting on a spectacular display, seen while driving on S2, for at least 12 years! See: