An excellent read on crop circles (which eventually led me to this board) is The Cosmic Connection by Michael Hesseman. 1996 I believe.
I wouldn't take your bet if more than just design was required. Some have become very adept at creating excellent looking circles at night and in one night. The key, is when circles have the other traits as well as perfection in design - and there have been some very near perfect (if not perfect) circles and designs. Check out the mandelbrot for starters.
There have been interesting stories of Gov't perpetrated hoaxes. Whether or not they are real is not for me to say, but the witnesses are highly credible and extremely well thought of. I think it's a big story that is under reported and the hoaxers are an unfortunate impediment to serious pursuits of researchers and possibly all mankind. I know it sounds funny when I say mankind but what if the lines of communication are being blurred a purpose? Too much sci-fi for many-all of them previously indoctrinated in the absolute science which states that nothing moves faster than light. How is it that we can actually know for sure. I've certainly opened my mind to the existence of E.T.'s.
In essence/honesty, that's what we're talking about with crop circles. If they are not man-made (if we/society are to believe that ALL of them must be hoaxes), then someone else is responsible obviously. Let's see, man is the only animal smart enough to create something like this and if he didn't do it, well, one can't start looking to the prairie antelopes now can we.
May seem funny to some but, what if, and granted a big if, the 'gods' of old have come back or never left etc.. Just a question.