WPSU carries Thistle & Shamrock, but not two other folk-oriented NPR shows that I listen to whenever I get the chance:
Both are quite eclectic (which suits me just fine), but contain a significant portion of what we all would agree is folk music. They can be found under “Music Programs” at npr.org/music. You can listen to and download songs, or even whole sets.
Then there is the website
with 24/7 streaming, hosted shows, listener ratings of the top songs of all time…