Here is a basic family tree someone has up of the relevant families:
http://www.wikitree.com/wiki/Underwood-2473The names to walk back in generations are Perry Leonard Underwood, Oliver Perry Underwood, Silas Dinsmore Underwood, Druscilla (Morgan) Underwood.
Druscilla (Morgan) Underwood is the main ancestor that Paula claimed was given special Oneida teaching stories.
In all census, all generations, everyone is listed as white.
Paula knew her actual genealogy, she used it in her books, her family history research was donated to a library, and I found a copy of her genealogy application to join the Daughters of the American Revolution for another branch of her family tree. She knew her people were white settler colonials.
Yet she claimed that she was Iroquois, or that her family for generations was entrusted with Iroquois teaching stories.