Alongside the money tree at Becky Falls is the following description:

“Nobody knows the exact origin of the Money Tree, but local legend has it that many years ago, this path was the main route from the Moor to Bovey Tracey. It is said that a huge serpent lived in the brook and ate the occasional unsuspecting traveller. In order to ensure safe passage, the pixies would apply an invisibility charm to any traveller, so long as they paid a small toll by placing a coin in the tree. This ensured safe passage. However, if you take a coin from the tree you will incur the wrath of the pixies.”

(via hannaclemence)