Thanks Steve, here is some info that a friend found for Mountain mahogany.
Mt Mahoghany (cercocarpus ) is a small tree/ bush that grows at higher elevations out west. The largest ones I have seen are about 8 inches in dia. I have seen it in eastern oregon, and all the way down to SW utah. I've made tool handles , foreshafts, and a boomerang out of it. Incredibly hard- s.g. is about .90 . hard to find a big enough piece for a bow- i searched a grove near glass butte for hours and came up with a piece about 45 inches long with knots all over. never seen it in WA.