PSUSA: IMO some of them are much too complicated for people to have done in one night, and especially not leaving a trace.
Below, Jaime Maussan (commentator from Mexico) shows a bit more than just some pictures but on the ground and sky views of the phenomena. It is an excellent series if you are interested in this detail. It is a little rough for those lacking Spanish but it actually is the best documentary I have seen for last year.
I[t] is about 60 minutes of your time. Crop circles are fantastick.