People who research crop circles in a serious scientific manner are in little doubt that human beings are very good at making them. But there is also no scientific doubt that some crop and soil anomalies in and around crop circles are created by microwave radiation. It is proven, by scientists, that the crop and soil have been superheated by a method which as yet has no explanation. This does not mean that aliens are attempting to communicate, but many of these irradiated crop forms create recognisable symbols when viewed from the air, a dragonfly for example.
If you have the fortune to reach a microwaved crop formation before anyone else arrives you can see very clearly that the crop has not been flattened by boards, in fact it may not be flattened at all, the stems are often upright and then bent over at nodes above ground level.
Scientific studies by BLT research may be of interest if you want to know more about the subject.