Mary S. Williams (maiden name: Sturdevant) was born around 1817 in Connecticut. She married Benjamin Burroughs Beach on November 2, 1834, and they had at least five children: Hannah, born around 1836; Edwin, born around 1839; John, born around 1841; Mary, born around 1848; and Helen, born around 1851. They lived in New Milford, Connecticut, and her husband worked as a painter. They moved to LaSalle County, Illinois, in the 1850s, and her husband probably died in the 1850s.
She married Robert B. Williams in LaSalle County, Illinois, on January 17, 1858. They lived in Deer Park, Illinois, and her husband worked as a farmer. By 1860, they owned $8,000 of real estate and $775 of personal property. A decade later, their wealth had grown to $12,000 of real estate and $15,000 of personal property. She probably died in the 1870s.