folk song 
noun
A song that originates in traditional popular culture or that is written in such a style: a Scandinavian folk song [mass noun]: this type of rhyme has survived only in folk song...
- Whether she is singing a traditional folk song, a ballad, or a song with a message, Baez is a singer without compare.
- In this compilation, appropriate music has been added, often based on folk songs or popular songs of the time.
- Among the most popular styles of folk songs are love songs and patriotic songs.