[Nedusa]

Am forced to concede these must be man made as I cannot come up with a rationale as to why An advanced Alien race would travel hundreds of light years across space and possibly time just to make a few pretty patterns in a corn field before shooting off back to the Delta quadrant.

It really makes no sense and if you apply the theory of Occam's razor then the simplest explanation is normally the correct one.... Ie man made almost a form of art now but man made nonetheless.

Some lovely baffling designs I have to admit...