That looks like some nice stuff. I was curious too and did some poking around. I think it might be Amorpha fruticosa, the false indigo bush. I vaguely recall reading somewhere that they make really nice shafting, although Ive never found the plant in my area. Id get a sample of the leaves and further investigate as well as visit the plant during its flowering season to be 100% sure. It always bugs me when I don't know what material Im working with... Anyways, first posting here, been reading for a couple years atleast. Good to be here. Hope that helps.