I had a good crop on A. tegmentosum last year, Krist (and have several seedlings growing now). This year very poor seed set, and by now the seed is all gone anyways. Remind us again next year - but in september!
I suppose a small seedling is no good for your use, otherwise I would offer to smuggle one in the post for you.
Incidentally the mouse populations are huge in our area this autumn, and I am worried cause it can spell disaster for many yooung trees and shrubs, like the A tegmentosum. Have seen examples where all bark from the ground and one meter up is all gone in spring. The good thing is that I hope for a good season in my nesting boxes for owls. Have checked one box wich contained a food chamber of more than 20 mice allready. Die! Die! (sorry about this last brutal outburst)