Some twenty years ago, I remember reading in the Austin American Statesman of people who went from town to town in areas such as the Appalachians, meeting up with elders, asking them to sing them any tunes they remembered. The people responded as though they felt humbly honored. For a while, the old American music - folk, bluegrass, blues - was being noted. Some of it was archived - preserved via the Smithsonian Institute which respects and carefully preserves all sorts of relics of the American culture and history.
One of my favorite folk songs is the Bells of Rhymney, which is European in origin, a song about injustice to miners. Many folk songs have to do with socio-political issues such as war or racism or unfairness to workers with few rights and at the bottom end the pay scale. There are also folk songs that are about love, drinking, animal tales, local news of the times. There is quite a catalog of songs for children, and that children have liked to sing. Another favorite folk song of mine is a lullaby - All the Pretty Little Horses.