I was lucky enough to attend all the Fox Hollow Festivals. I have never forgotten them. The best singing was at night, on the grounds.
The staff and the performers were allowed to camp on the grounds, which was great because the nearby campgrounds (like the Little Hoosik) always flooded out. I performed with Roger Sprung's Progrssive bluegrassers and I also played backup for whoever needed a bassist or a lead guitarist. What a lineup of traditional performers they had, Gordon Bok, Jean Ritchie, Jean Redpath, the entire Golden Ring (they're the ones who usually led "Bright Morning Stars" and "Pleasant and Delightful") and Bob, Evelyn and Marty Beers.
The finest introduction I ever heard was when Bob Beers walked out onto the stage holding a thick twig and a penknife. As he sang a song about a shepherd making a whistle, he whittled away at the twig and, as his song ended, he had fashioned a functional, if limited, whistle of his own. He blew through the twig, produced a sound and introduced The Pennywhistlers. I still get a thrill from the memory.