Hi Kathy,There's a session at the Starry Plough in Berkeley on Sunday nights, a number of blue grass sessions are in the area as well. Bay Area fiddlers check in here pretty frequently, they will have more complete information. Become a member (it's free) and send me a personal message, so we can work out details of places you can go. If you sing I can be of much more help, that's where I have the most experience. I also know where to find the best pints!
Dave