The Northern California Chapter
American Bamboo Society
San Francisco Bay Area Bamboo
South of SF there are the Hakone Gardens in Saratoga and the bamboo garden at Foothill College in Los Altos Hills.
In SF itself there is the SF Botanical Garden in Golden Gate Park with several nice plantings (some needing grooming!) and scattered urban sites with landscaping utilizing bamboo.
North of SF in Sonoma County is where Bamboo Sourcery is and I wouldn't miss it, nor a visit in nearby Santa Rosa, to Jesus Mora's Oasis Bamboo nursery. Both locations are well worth the 1½ hour or so drive north of the City, crossing the Golden Gate Bridge on the way.