i suggest connecting with the s.f. folk club..www.sffmc.org
they hold sings, festivals, camps, etc and
you can most certainly find others there!
here is a listing of the blue grass association
about the hootenanny of the S.F. Folk Music Club
http://www.cbaontheweb.org/calendar/showEvent.aspx?eventID=6560
http://www.sfhootenanny.homestead.com/
Faith Petric is the Momma of this group
Friday Night Jams at Faith's House
Faith Petric, the guiding light of the SFFMC, has been hosting acoustic music jams at her house every other Friday for more than 40 years. To read about Faith and the bi-weekly jams, go to this SF Chronicle article:
http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/09/30/MN15227.DTL
( it hink that means bi-monthly (twice a month) not bi-weekly)
Jams at Faith's Every other Friday. 8:00pm
885 Clayton St. (Carl and Parnassus) in San Francisco
415-661-2217

good luck and happy hunting...