Reynolds was born on July 26, 1824, in Sempronius, New York. In 1848 he married Mary Jane Smith, one of Wisconsin's first female physicians. He graduated from Rush Medical College in 1851 and moved to Ives Grove, Wisconsin in 1854. During the American Civil War, Reynolds was a surgeon with the 3rd Wisconsin Volunteer Cavalry Regiment of the Union Army. Reynolds died on January 19, 1911 in Lake Geneva, Wisconsin.
- Biographical Sketches. Wisconsin Blue Book. Retrieved 2014-02-01.
- Gregory, John Goadby. 1932. Southeastern Wisconsin: A History of Old Milwaukee County, vol. 4. Chicago: S. J. Clarke, p. 473.
- "United States Veterans Administration Pension Payment Cards, 1907-1933," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QJDQ-4MMM : accessed 28 July 2015), Benoni O Reynolds, 1907-1933; citing NARA microfilm publication M850 (Washington, D.C.: National Archives and Records Administration, n.d.); FHL microfilm 1,635,906.