Pleasanton is a city in Decatur County, Iowa, United States. The population was 32 at the time of the 2020 census. Pleasanton was fo…Pleasanton is a city in Decatur County, Iowa, United States. The population was 32 at the time of the 2020 census. Pleasanton was founded in 1854. It was originally called Pleasant Plain, but the name was changed to avoid confusion with another community of that same name in the state. The present name is commendatory.