Alan Arkin was one of those Washington Square folksingers from the late 1950s. He recorded an album of children's songs with The Babysitters, a group that included Lee Hayes and Ronnie Gilbert. His brother, Steve, is a talented bluegrass banjo player who played with Bill Monroe for years. I saw Steve, recently, at a Washington Square reunion.
Quite a few well-known performers were into folk. Eddy Arnold, the Tennessee Plowboy, recorded an album of traditional songs that included the most beautiful version of "Wayfaring Stranger", and what a beautiful voice he had.