The earliest known crop circle, known as the "Mowing Devil," is shown on this woodcut from Hertfordshire, England, 1678. The inscription on the woodcut is as follows:
Being a True Relation of a Farmer, who Bargaining with a Poor Mower, about the Cutting down Three Half Acres of Oats: upon the Mower's asking too much, the Farmer swore That the Devil should Mow it rather than He. And so it fell out, that very Night, the Crop of Oat shew'd as if it had been all of a flame: but next Morning appear'd so neatly mow'd by the Devil or some Infernal Spirit, that no Mortal Man was able to do the like. Also, How the said Oats ly now in the Field, and the Owner has not Power to fetch them away.
Liscensed, August 22nd, 1678.
Hemel Hempstead The Mowing Devil