Here in my part of CA, we don't have osage, hickory or yew. But I pass tons of ash & mulberry every day. Plenty of Chinese elm, too, though I'm not sure if that's as good a bow wood.
I'm wondering how to select a branch to harvest for a selfbow. How thick should it be in diameter (minimum)? How can I tell how straight the grain is when it's still on the tree? Are a few small knots okay or does it need to be clear? there aren't too many folk who do this sort of thing out here (I have one trad-hunting neighbor but he's not into building). Any good resources for learning?