Actually, I looked at your tree and figured that out.
You probably already know this: The Library of Congress does not have a copy, all the top used booksellers do not have a copy, "Books we Own" does not list a copy, WorldCat doesn't either. I'm thinking that maybe only one book was printed?
Have you tried the historical societies, genealogical societies, libraries, museums, "ethnic" societies, women's societies, lineage societies -- all in the local towns, counties where she lived? or the schools she attended? She may have donated copies to them.
Otherwise, I think you're going to have to go to the Mississippi archives to see it or hire a genealogist.
Another thought -- Who was her heir? Could he/she claim they have a right to the original? (might not get anywhere, but worth a try...)