Mary Bagby was born in Castor, Bienville Parish, Louisiana, USA on 20 July 1890 to parents Rev. Dan Wedlaw and Elizabeth Jackson Wedlaw. Growing up under segregation, she made the journey from home to elementary school in the back of a horse and buggy. In 1918, her family moved to Depew, Oklahoma, before later arriving in Madera, California in 1936.

She was one of the first members of the second Missionary Baptist Church, which was just a block from her Madera home. Raised in a religious household, she continued to pray on a daily basis and read the Bible into her final months. She was fond of Snickers bars, and looked forward to them every time her caretaker, Lorraine Rhone, went to the grocery store.

She passed away in Madera, California, USA on 31 October 2001, aged 111 years, 103 days. She was survived by her sister, daughter-in-law, grandchildren, and great-grandchildren.