Dipping into the slightly more obscure, the old EUB Hymnal contains a song called "My Heart Looks In Faith" the tune for which is listed as a Chinese chantey "Song of the Yangtze Boatman". The Methodist Hymnal includes folk tune listings in its index of composers, authors and sources. The great methodist hymnwriter Charles Wesley was a wordsmith and not a tunesmith. Thus many of his hymns are put to tunes by others, some of which are folk tunes. Here are a couple from the 1964 edition.

"Come, Let Us, Who in Chirst Believe" tune Campmeeting (early American)
"How Happy Every Child of Grace" tune Cleansing Fountain (American usually associated with "There Is a Fountain Filled With Blood")

The traditional English tune "Forest Green" is listed for 5 hymns:
All Beautiful the March of Days (Frances Wile)
I Sing the Almight Power of God (Isaac Watts)
O Little Town of Bethlehem (Phillips Brooks)
And Have the Bright Immensities (H C Robbins)
Eternal God Whose Power Upholds (Henry Tweedy)

I am sure there are more

rich r