I reference to your question about Rebecca Walpole Garner (on genealogy.com) I purchased an old book called "Special Texas Edition Garner of Texas" by Bascom N. Timmons copyright , 1948. It is an biography of John Nance Garner the fourth, the Vice president under FDR during his first three terms. On page 2 it talks about Rebecca Walpole Garner. This book indicates that she was a direct descendant of Sir Robert Walpole of England Prime minister and parliamentary leader of the early 1700's.She was apparently the Grandmother of John Nance Garner the forth, she was married to John Nance Garner the second. The Garners left Rutherford county Tennessee, to Blossom Prairie, Texas around 1851. Rebecca was apparently a widowed prior to this trip made the trek by herself with six children three boy and three girls. One of these boys was John Nance Garner the third, the father of the vice-president (his wife was Sarah Guest). The other Sir name that is listed in this book is the Nance family of Virginia and Tennessee. apparently Rebecca was part of that blood line.
I doing some research myself so I know how difficult it is to obtain info. If I can be of further help let me know. Additionally, if you run into any info on the Garners from Texas, Virginia, Tennessee, Georgia or South Carolina I would be interested.