Shell casing from Normandy Beaches, D-Day 1944

One brass shell casing (2012.8.2.4a) stored in a cardboard tube (2012.8.2.4b). The casing has an imprint on the headstamp: [P / unidentified mark / unidentified mark / 20]. The tube has the inscription: "Shell casing from D-DAY JUNE 6, 1944/From: M.Sgt. Wallace B. Jackson/To: Hattye M. Thomas (Yarbrough)" written in blue ink. This shell casing was retrieved from a Normandy beach on D-Day, June 6, 1944, by Master Sergeant Wallace B. Jackson of the 320th Barrage Balloon Battalion and sent to Hattye T. Yarbrough, an educator and wife of a veteran.