Collecting “souvenirs” was a practice common during World War 1. Colonel James C. Hughes kept this German hand grenade from his time serving in Europe as part of the 35th Division.
Hughes, a Kansan, is among a select number of soldiers who served in a major military expedition as well as two world wars. As a photographer took more than 600 images documenting his time at the Mexican border in 1916 and in Europe during 1919. As a Japanese prisoner of war in World War II, Hughes kept a daily diary and, upon liberation, brought home items from his imprisonment. He and his family donated most of these items to the Kansas Museum of History.
More information at: https://www.kshs.org/kansapedia/james-clark-hughes/19881