It's Certainly Man-Made But It's Interesting Regardless:

Another crop circle has appeared in the English countryside — and this one's clearly been made by someone, or something, that understands math.

At first glance, the strange ratcheted pattern, radiating out clockwise, doesn't look like much — modern art, perhaps.

But an electrical engineer from North Carolina — described by the London newspapers as a "retired astrophysicist" — figured out that it was an abstract representation of pi, the number at the center of Euclidean geometry.

The article says 'word quickly got around the crop-circle community'. I was unaware that such a community existed in any significant numbers but, hey, who am I to say what's significant. It's been proven time after time that these crop circles are man-made but that doesn't make them easy feats. I have to say, I'm impressed.