In the U.S. the Field Recordings (proper noun style), were made by Alan Lomax
during the 30's and 40's for the Library of Congress
Lomax crisscrossed the country recording anyone of local repute out of the back of his truck. Leadbelly even worked as his assistant for a while after Lomax recorded him.
He made the first recordings of everyone from Robert Johnson to Muddy Waters. These are true American treasures of music.