I find this to be a most interesting thread. From here it looks like who was a 'lesser known group' depends on where you were when they were active. For instance, here in SoCal I would not have considered the Dillards, Tarriers, Gateway Singers, Bud & Travis or Chad Mitchell Trio, among others, as lesser.

In various incarnations the Gateway Singers had Lou Gottlieb and Travis Edmunson, who went on to other groups. And Travis' partner Bud formed Bud Dashiell and the Kinsmen after B & T split up. The Whiskeyhill Singers (mentioned early on) was formed by Dave Guard after he left the Kingstons, and had as the obligatory girl member, Judy Henske.

The New Christy Minstrels was originally made of of lesser known acts -Art Podell, mentioned above somewhere, and BARRY McGuire & BARRY Kane come to mind.

Of all the groups previously cited, my personal favorite was (were?) the Travelers 3. My favorite of all (and not previously mentioned)was Terrea Lea, who operated the Garret Coffee House in West Hollywood, just her voice, an acoustic guitar and the expresso machine; that was folk music!

John Hindsill