It is suggested by some cryptologists and others that crop circles are depicted in prehistoric stone and wall carvings, such as in the spiral patterns carved in a stone at Newgrange in Ireland. For those that hold the view that crop circles are created by extra-terrestrials in spacecraft, some would say that reasonable recorded proof of this is depicted in some ancient Egyptian pictures.
Crop Circle Garden Gate. This Julia Set Fractal appeared as a sensational crop circle, opposite Stonehenge on 7th July 1996. It contained 151 circles and measured 915 feet along its spine. Some of the centre twists were truly complex and would have taken an age to do just on their own. The gate has saloon style hinges, which open both ways, towards or away from the "glow" and is yet to receive its final paint job. pw limited.co.uk
This one reached the front page of many newspapers. The message is getting through! A 780 ft (240 m) crop circle in the form of a double (six-sided) triskelion composed of 409 circles. Wiltshire, UK. 2001.