As far as I know, soapwood (Clethra occidentalis) grows exclusively in the Blue Mountains of Jamaica. If memory serves me right it's a small scrub tree and not harvested. Of course, soapwood is also a name the southwest native Americans gave one of the varieties of Yucca, but I don't remember which one. Of course, as with many common names (like ironwood), there could be any number of trees aroud the world with the common name soapwood.