Have you looked at the California Indexes on ancestry.com?

Example...Birth Index for Contra Costa Co. shows 61 BRADSHAW births from 1905-1995, lisitng gives b'date & mother's maiden name.

Death Index for Contra County lists 51 BRADSHAW deaths from 1940-1997 gives death date, b'place (State) & mother's maiden name.

Marriage Index for Contra County list 47 BRADSHAW marriages spouses & marriage date.

Divorce Index 1966-1984 for Contra County list 39 BRADSHAW divorces...spouses & date of divorce.

Seems as if these California Indexes could give you some outstanding clues to work with in Contra Costa County as well as all other surrounding counites for the BRADSHAW surname.

Just a thought,

Art Thomas