Hello, I want to buy Bitcoins for cash(bank transfer or W Union ) in US ( is preferred San Francisco ) who can help ?
Localbitcoins.com should do the job for you , I'm personally from Algeria and I can't really do much for what comes to cash but since you are USA there shouldn't be anything to worry about and I'm sure you will find a lot of people willing to do that .
Otherwise you can search in currency exchange section for people willing to trade with you in San Fransisco like you mentioned or they mail the cash to you (using an escrow of course) .