I was astounded when you mentioned they are becoming invasive.......and checked it out to find that in certain localities they are. Seems they can go in this direction where summers are cool. Mine doesn't go the nice red in autumn, but a dirty gold........some amurs will. And I never have a heavy setting of samara and am just now finding a few volunteers under the tree and it's been there maybe fifteen years or more by now. Mine is gorgeous and thriving.........but our summers can be hot and I suspect it affects the reproductive capabilities.

You're right - that isn't much to go on! With perhaps 500 named cultivars in commercial trade and many fitting roughly that description, not to mention a few dozen more cultivars of shirasawanum and japonicum that most folks think are also J. maples, any guesses would just be a shot in the dark. Fortunately the Puget Sound area of Washington state is home to dozens of excellent nurseries, many featuring large selections of Japanese and other Asian maples. A number of public gardens and arboreta also have maple collections you can view for comparison. We have just peaked with fall color on most maples in this area and they are starting to drop leaves, so now is perhaps not the optimum time to select based just on fall color. One cultivar you may want to pursue is 'Osakazuki', which is known for stunning fall color. Pretty popular in this area, it will develop a rather horizontal branching pattern and is often sold multi-trunked or with a very low crotch. It will get quite a bit larger than 12-15' in time, ten years being rather young as J. maples go.

"A pic" is not enough, white mulberries are polymorphic. And weedy. That's why people ask about them repeatedly: they don't recognize one of the many different leaf shapes they produce, and they pop up all over.

Expensive grafted named cultivar coming from Arbor Day seems pretty unlikely. Especially if it was free. Tree looks like a typical wild-type seedling. So it is likely to produce a small (15'-35') vase-shaped tree that will take many years to reach full size.