This shirt and hat were donated to my collection today. They both came out of a Klamath Falls, Oregon, surplus store decades ago. The thought was that they came from Camp White, Oregon, where German and Italian POW's were interred during WW2.
There's nothing special about the shirt other than the PW markings. The shirt has seen a lot of zig-zag repairs which is probably why it was down graded for POW use. The cap is unmarked.