http://www.archive.org/stream/naeniacornubiaed00borl#page/215/mode/1up

I quite like to look up what early authors about antiquities have to say, even though some of what they assume is proven wrong later, they sometimes include lesser known local folklore, and their books are aesthetically inspiring in an olde worlde kind of way.

Plus, I'm assuming you know the wikipedia stories related to the site, and this book gives another legend rarely referred to now.

In 1907 an Englishman bought the farm where the Merry Maidens stone circle stands. Thinking that the stones lessened the value of the field, the new owner ordered one of his workers to pull them down and add them to the stone walls surrounding the meadow. The worker, a Cornishman, protested, but the Englishman insisted that it was his field and that the worker should do as he was told.

Next day the Cornishman hitched up three shire horses to a chain and began the task. As they began to pull over the first stone, the lead horse suddenly panicked, reared up, then fell over dead.

Reporting this to his master, the Cornishman asked if he should fetch another horse for the task. "No," said the landowner. "Set the stone back upright. We'll pull the lot of them down later."

But the stone circle was left undisturbed, and remains so to this day.

The pagan legends would most likely have been of the nine maidens type, where nine or eighteen maidens are led by a mother (rarely a father) figure, making a total of nineteen.