I took your suggestion and did a little reading. The CircleMakers web site was particularly interesting. Especially the testimonies of circle makers that went out to see if they could duplicate amazing and unexplainable circles that had been discovered. Not only did they duplicate them, they made them even more intricate and got a chuckle out of the media and experts the next day that said it was impossible for a human being to have made them.
Some of the pictures at the web site are amazing... they really do nice work.
Those pictures are not of any they did. These guys are "spoofers".