I'm tracking O'Flynn's as well. Here is as far back as I can get. One lead I heard about lists Timothy O'Flynn as John O'Flynn's father with his wife as Sarah (unknown). Maybe Sarah Dennison but that may be the wrong tree.
John O'Flynn, Sr. born 9/5/1848, died 8/8/1919 -- Paulding Ms.
Married Katherine Carr, born 7/13/1855, died 5/24/1916
Their kids were:
James Timothy O'Flynn Mar 2, 1880, died Jan 20, 1968 (married Emma Sebastian Daly)
John O'Flynn, Jr.
Florence O'Flynn Tarbutton