The Plum Grove School District was formed in 1863 and was located about 5 miles northeast of Oskaloosa near 122nd and Saline. In 1950, the school building was moved to Oskaloosa and became part of the elementary grade school complex for grades 1-4, along with Kilgour, Tibbott, and lumber from Lone Tree Schools. In 1975, the combined Kilgour/Plum Grove Building was relocated to Old Jefferson Town. It presently houses the Jefferson Co. Genealogical Society Resource Center (Library).