The Faerie ring is created by the residual energies left from the Fae magick. Witches often hunt out these sacred places and perform their rituals there, drawing upon the energies of the Fae. A Faerie ring is a Sacred Circle created by the Fae. A fairy ring in a field beside a house is a lucky omen.
During the witch trials in Europe in the late 16th and early 17th centuries, real witches would hand a person an acorn to signal to them that they are a practitioner of the Old Ways. Acorns are sacred seeds of the Oak tree.