From the record
“Conant's Cabin and Park, also known as the Rural Wayside Rest and Recreation Site, is a private park located east of Gladbrook, Iowa, United States. It was built in 1920 by local resident George Conant on 15 acres (6.1 ha) of farmland that he owned.”
Wikipedia article Conant's Cabin and Park, CC BY-SA 4.0.
One of 14 National Register listings published here for Tama County · listed in 2000 · category: Building · built in 1920, American Craftsman.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service · the Wikipedia article