One interesting article that your colleague may want to look at for ideas is
Janet Siskind's article in *Critique of Anthropology*, v 12, pp. 167+, 1992.
Siskind has some interesting ideas and a good content-over-theory biblio that
may contain more good sources of info. on alternative interpretations of Turkey
Day. Oh, the article is entitled "The Invention of Thanksgiving: A Ritual of
American Nationality." Bon chance!
Best regards,
John Stevens