Have you looked at Wildseed Farm
http://www.wildseedfarms.com/ ?
They have a great variety and sell mixes for specific areas of the country including the northeast.
You don't seem to be sticking to strictly native plants, so I could suggest foxglove and a nice native would be penstemon. You didn't mention ox eye daisies or chicory and also native autumnal asters extend the season.
