Fey mounds were hidden burial barrows of wild fey which often contained treasures buried with the fey. The soil from fey mounds was thought to be magical and was used in some rituals to increase the fertility of fields. Individuals highly attuned to magic could sometimes sense a mound's presence.
Mounds were often protected by illusionary magic which could charm trespassers or cause them to fall asleep. Living fey zealously guarded mounds and punished those who disturbed their kinsmens' eternal rest.