WWOOF or something similar

Hello friends!

So I live in San Francisco and am looking for a place where I can help out a couple of weekends a month. I work full-time and can't afford to take weeks off to dedicate to WWOOFing. But I would be all up for driving a few hours to spend some weekends helping out and learning as much as possible. If anyone has or knows a place within 3-4 hours of San Francisco, I would love to hear about it!