Well... In every case where we know how they were constructed, they were made by humans. And, by the way, it's not a hoax, it's *ART*.
The perfect design and perfect bending over of the crop in some cases makes me think they can't be all hoaxes.
Perfect design as seen from a mile away? BFD.
Perfect bending over of the crop? How many have you seen up close? How many have you touched? You don't think the makers have more than one construction technique?
Again, it's not a hoax, it's *ART* - that's why they get permission from the field owner.