My first instinct would be Southwest, like Texas.
Here’s an article with maps that show the Census regions that @Jackcooper@lemmy.world mentioned puts OK in the South: https://www.businessinsider.com/united-states-regions-new-england-midwest-south-2018-4?op=1
And here’s a map from National Geographic that puts OK in the Southwest: https://education.nationalgeographic.org/resource/united-states-regions/
American here, but I agree with a traditionally Polish or German gift. I’ve always thought Polish pottery is lovely.