You should be able to get these state-side. There's the one I mentioned a few posts above, Minamoto Kitchoan, who have a store near Rockefeller Center in NYC.

There's bound to be other wagashiya near SFO/SJC, etc.

EDIT: Here are some more locations for this company:
http://www.kitchoan.jp/ovsshop/index.html

If you have a Mitsuwa near you, that would probably work too.