It's referring to a short pulp fantasy story one of the writers of the episode wrote, which appeared in Astonishing Adventures Magazine #8.

She had just referred to "Clover Hill folks," so that's the hill she's talking about.

This is probably a joke, but in case it isn't, I think she was referring to "Clover Hill" which she had just mentioned. (that she saw him hanging out with "Clover Hill Folk.")

The elder statesman of the hill clan's name is "Cope," not "Colt."