No, I am not. I think they are all man-made. Since they all use the same tools to create them with similar methods, the results would be similar. To give an example of what I mean, if you are familiar with the old toy a Spirograph. You can make different designs (with a lot of variety), within the limits of the tools the Spirograph provides.

http://en.wikipedia.org/wiki/Spirograph

Crop circles are usually made with boards (to flatten the crop), string and/or measuring tape (to make the circle geometric), and markers of some kind as well as a design (which in one of the videos I linked the crop circle makes said they sometimes change on the fly if an error is made in the initial layout).

Your assumption about me is seriously flawed and incorrect. It's only a hoax when people do it try and fool others (which some do) others do it for artistic reasons and do not hide the fact. I believe they are all man made and very possible -- People do bizarre things for strange reasons all the time.