Green box elder turns very nicely. Only problem is it's a fairly soft and wet wood and, as it dries, it will move quite a bit. Any figure in it will raise and sink till it's distinctly no longer flat. Once dry, it will tend to tear out if not careful. Big fan of rough turning it green, letting it dry (don't wax it or it will spalt all over the place, plus I haven't found it to check that bad when drying) and finish turning it.
Turned a vase out of Russion Olive last night. Whew! As stinky as box elder, but different! Same goes for red oak, which smells like pee and turns your tools and hands black (love it though). Going back to cherry and apple for a while for a while for a nose break.
Dietrich