Butterfield is a city in Watonwan County, Minnesota, United States. The population was 601 at the 2020 census. Butterfield was platted in 18…Butterfield is a city in Watonwan County, Minnesota, United States. The population was 601 at the 2020 census. Butterfield was platted in 1872. Butterfield developed as a railroad town and was incorporated on April 5, 1885. The community was named for William Butterfield, the original owner of the town site.