I never heard any English language multi-part folk songs, I'd come to believe they don't exist so I'm really interested in this thread. A lot of the time, folk comes to mean a song in English interpreted by a soloist in a particular story-teller style. Which is (ahem) a little bit restrictive.

In French I know several multi-part traditional, popular (in the sense of from the people, by the people etc.) songs. Start with "canons": frère Jacques is a four-part song!

1st singer starts

Frè Jacques, frè Jacques

2nd singer starts (from top)

Dormez-vous, dormez-vous

3rd singer

Sonnez les matines, sonnez les matines,

4th singer

Ding-din-don, Ding-din-don.

I'll add a few in a separate "French canons" thread. Canons are so familiar to me that I'm not sure how to explain how they work... The word canon (artillery gun) comes from the rolling sound of a battery of guns fired one after the other.

Aux marches du palais (words in the French lyrics request thread, can't find the reference because my browser won't access the darn thread listing now) is a duet, and the tenor part is lovely. Belle qui prend ma vie (in the DB) is a four-part song though it's hard to count as "folk". It's not the kind of thing someone's grandmother used to sing.

Do Negro Spirituals count as "folk"? And welsh choirs?

Charles