If you like back-country music, check out "Cindy" (Git along home). A few good ones there.

Some classic Lale Andersen for those interested in songs popular in Germany in WW2 and following decade. I started by recording several from youtube, then ended up buying every compilation of her songs that I could find. Also a sucker for Vera Lynn, and others of the WW2 era.

Some fine Django Rinehardt, esp. Nuages.