In response to the request for information on historic seeds, there have been
several articles on the subject in issues of the magazine "Country Living"
over recent years.  My own issues are packed away at the moment, but I recall
an extensive article on a specific farm (Connecticut, New Hampshire?) that is
devoted to the discovery and cultivation of historic plants.  While this is
hardly a scholarly source, you might come up with some interesting contacts
by getting in touch with the magazine.  I believe they have a Web Site as
well.
 
Hope this helps,
Karolyn Smardz