WPA Stock Barn and Pavilion, also known as the Rock Barn, is a historic barn and pavilion located at Trenton, Grundy County, Missouri. It was built in 1938 as a Works Progress Administration project. It consists of a two-story, octagonal barn with attached one-story stock pens. The building is constructed of native stone on a concrete foundation. The building served as a livestock housing and sales pavilion for the annual Grundy County agricultural fair.
It was listed on the National Register of Historic Places in 1994.