A leprechaun was a type of faerie.
In 1934, a member of the Adventure Society traveled to Ireland in search of faerie treasure and found a leprechaun who then fled. The Society recruit gave chase and when the leprechaun was caught, he professed to be a simple shoemaker despite the patches of clover that had been sprouting up in his wake.
Encouraged by mentor Professor John Allen, the Society member went on to discover the leprechaun's treasure, which turned out to be a large hoard of footwear.