Just don't say you know the answer - as if all crop circles were trampled by people :)
Jokes aside, I personally believe that natural crop circles (as opposed to man-made ones) are the work of a more advanced intelligence and may hold the key to a deeper understanding of our Universe.
I believe that the creators of crop circles (various civilizations) have access to another dimension and also exist there themselves (most of them). At the two-minute mark of this video, we can see the "device" used to create the circles.
The image of this device has appeared in fields several times in different years. I think we need to translate this drawing into a 3D figure and think about what kind of device it might be.