The coin must have been secretly placed in the menhir by some pious peasant as a direct ex voto for some favour received or demanded.
"The Fairy-Faith in Celtic Countries"
W. Y. Evans Wentz
The place in the menhir where this coin was discovered is on the south side about fifteen inches above the surface of the ground.
"The Fairy-Faith in Celtic Countries"
W. Y. Evans Wentz
Disappointed at a failure like this, which for him was most unusual, Cuchulainn went away to a menhir where he sat down and fell asleep.
"The Fairy-Faith in Celtic Countries"
W. Y. Evans Wentz