If one believes that some of the "real" crop circles are not made by planking (human creation) then there are a number of interesting theories to explain how the crops are bent. Rapeseed, one of the favorite mediums, is a very brittle plant which usually will break if the long narrow stalks are bent. While there are many broken stalks in the crop circles, many plants exhibit a very unusual phenomenon where the "nodes" are bent, not broken.
Just like bamboo grows in segments, rapeseed stalks have segments which are connected by a special formation called a node which has the ability to be somewhat dynamic and orient the growing plant to maximize exposure to the sun. The node is not flexible, but it does have active cells that can grow quicker on one side or the other to change the plants orientation.
In "real" crop circles it has been observed that the nodes are often bent -- sometimes at 90 degrees -- and this accounts for the horizontal positioning that makes the designs of the crop circle. Other nodes exhibit holes in the nodes, while surrounding crops show none of these changes.
One good theory is that some sudden and extreme heat source has cooked the moisture inside the crops, causing the nodes to become soft (as if steamed from the inside) and, in some cases, to pop open under pressure. Indeed this has become the objective method for determining if a crop circle is "real" and samples of the plants are now routinely gathered for this assessment.
Yup, also the wheat in several circles have been reported to be standing vertically for several inches and then bent over at 90 degrees, whereas a simple plank would flatten the wheat at the very base of the stalk.
Thanks for posting the first post here on the community that wasn't made by me! Hope to see more activity here, tbh it's kinda strange how quiet people are about this subject. I mean even if someone thinks they're all made by people, at least we can agree on the fact that they are beautiful artistic designs, right? I would like to meet the artist capable of pulling off some of these, human or not ;)
PS would be cool if you could make another "Physical evidence" post about the metallic spheres found in the soil under some crop circles that drops off in concentration the further you get from the middle of the formation, or how almost all of the ones in southern England occur over chalk aquifers, or how some formations return the next year in the form of a "ghost" formation, where the wheat/barley has grown differently due to changes in the soil made during the creation of the circle in the previous year.