I grow Californian poppies in my Rubble Garden, so-called because it's where the builder stockpiled sand and gravel. I started with a packet of standard orange, and another of mixed softer shades. They now self-sow (sometimes in the most unlikley places, as Umbrian suggests), but orange does seem to predominate. And yes, some of them overwinter, until they get too leggy and woody and I cut them out. Here's a photo of the Rubble Garden, which I have never watered and which is exposed to the worst of the wind.
Caroline