If you're interested in men's field hockey in the Southern California area, a good person to contact is Tom Harris. If you're in the Orange County/LA area, the point of contact for the area is  Manilal Padhiar, (714) 848-7072. Also, check out this link for Moorpark, CA field hockey information: Field Hockey Sports Center

For men's field hockey in Northern California (ie the San Francisco area), see the Cal Berkeley and Nor Cal home pages which are listed in the links section.

The Links section also lists a link to the USFHA listing of all clubs in California (including contacts).