American (or Chinese) chestnut is a great starch-source tree for those of us living in North America. Unfortunately, it's pretty huge for those of us living in cities. The chinkapin, a naturally dwarf, bushy cousin from the Appalachians would be awesome, but all of the stock I can find comes from the east coast, and thus harbors the Chestnut blight, making it either restricted (by nurseries who care) or morally questionable to ship it to Washington state -- Our american chestnuts are still alive because they never got blight, not because they are immune.
I haven't tried grafting any chestnuts, but a couple other ideas come to mind: bark inversions and partial girdling. I don't know if either of those would work with chestnuts, but both are used to dwarf various other trees.