When asked to supply organic milk for communal use at her flat, a friend bought Safeway's O brand organic milk. Her roommate was displeased, claiming it wasn't really organic. (Many greens question the substance of the USDA certification program.)
The same roommate, a native Californian, happily shops at Trader Joe's.
Why? Trader Joe's also carries private-label organics. The milk is likely produced in exactly the same way as Safeway's O milk.