There once was a folk/roots music mountain get-together cum festival at "Sweets Mill," a private camp east of Fresno, CA that ran for many years, beginning in the 1960's, if memory serves. I don't know if it continues in some form or if another venue has replaced it, but the late Mark Spoelstra, among others, was a semi-regular attendee. There is an active group of folk music devotees in the central San Joaquin Valley area. You might try contacting fresnofolklore.org for the latest.