Singing Stones in Walnut Creek is AMAZING and people come from all over the Bay Area to attend it. I can't really recommend it highly enough. It is on seven acres, has an organic garden, the kids spend TONS of time outside and even every other Friday in an off-campus nature spot (that varies).
They are a Waldorf school and they are extremely nurturing and, at this young age, have no focus on traditional "academics." And if you are daunted by the price they have an "accessible-to-all" philosophy and will work with you (seriously, they give me about 75% off of tuition because I'm a single mom and that's what I can afford). If you'd like to speak to me about it PM me your phone number and I'd be happy to. Good luck!!