My grandmother's maiden name was GAA. She was Loretta Gaa Witt. Her parents were Andrew J. Gaa (1887-1936) and Nellie Parle (1887-1946) from East St. Louis, IL and Belleville, IL. Andrew's parents were Martin Gaa (1847-1904) and Louisa Ulrich (1842-1912). The GAA family is originally from Hockenheim, Germany and moved from Germany to Upper Sandusky and Wyandot, Ohio. Martin Gaa moved from Ohio to East St Louis, IL (from which line I am then from). Martin's parents were Joseph Gaa (1824-1889) and Eva Katharina Wimmert (1825-1897). Joseph's parents were Johann Gaa and Anna ?.
If any of this sounds familiar or you can help, please let me know. I have some additional information that might help as well.
Thank you!