I am fascinated about how, even given direct evidence of people demonstrating how they actually made crop circles as a hoax, people still believe.
The basic idea that people follow to make the circles is covered with the image above right. You take a 2" x 8" (or equivalent in your culture) board about 4-5 feet wide. You drill two holes - one at each end - and pass a rope through to make a "handle" like the image depicts.
You then walk forward picking up the board under your foot, push the board forward while keeping it under you foot, and step down. This lays the plants under foot forward (in the same direction you are traveling). You then continually repeat this step.
(As a child growing up in farm country this is a totally obvious maneuver. As a small kid you had to do this with your foot to make a path through fields of wheat - which often pissed the farmer off.)
The big trick here, and why its called a crop circle, is the second rope.
The second rope is attached to something at the center of the circle, e.g., a stake, a person, etc. The persons stopping down the plants holds the other end of the rope (perhaps with a knot so that the position does not change) while moving around the center of the circle.
Now as children in the 1960's we had a toy called a Spirograph:
It came with a bunch of plastic "gears" with holes in them. You placed the gears inside larger "wheels" - also with gear teeth - and you placed a pen into one of a variety of holes in the "gears."
There was also the "Super SpiroGraph:"
As you moved the pen around the motion of the pen point was governed by the size of the gears and the location of the hole the pen was in.
The result, as you can see from the cover of the box, are "crop circles:"
Notice they all (for the most part) revolve around a center point (the center of the SpiroGraph "circle" wheel).
People always wonder how this could be done quickly and in the dark (assuming that a human couldn't get it done so it must be aliens).
Of course, with a pencil and string you can easily duplicate the "SpiroGraph" concept and test out your designs in the comfort of home with inexpensive tools you can buy at the dollar store. Once its working you merely "scale" up the string sizes to rope sizes and go about your work in farmer John's field.
There are tons of iPhone apps that do the "spirograph" functionality as well.
Of course there are still many "doubters" who are convinced that aliens are doing all the heavy lifting.
Chief among their "evidence" are things like this:
Showing that the crop circle plant stems have been somehow altered (N1) (full disclosure on how this must be aliens here).
Since its impossible to prove a negative I am not going to attempt to show that aliens didn't do it.
All this despite English pranksters Doug Bower and Dave Chorley revealing in 1991 that since 1978 they had personally made more than 200 crop circles (using the techniques I outlined above plus a few other tricks).
Are there natural phenomena doing these circles - perhaps in some cases - but most of the crop circles are too regular and formulaic to be natural.
Yet despite all of this people still "believe" (see this in Italy).
Today there are, of course, genuine "crop circle researchers" who invest a lot of time and effort and resources into "crop circle research." But this, like many other kinds of "research" has some problems.
First off, without capturing how these are made, i.e., unhoaxed video of alien craft creating one, and by ignoring the obvious (hoaxers coming forward with plausible explanations) its a little difficult to image what kind of research can be done. The planet is, after all, an "open system."
So while alien craft could be causing these circles so could humans.
This human idea of "believing" in something regardless of evidence to the contrary is interesting and seems to persist in science, i.e., climate research. Here we pick what it is that's causing some effect we observer and figure that it "must be" the cause, i.e., man-made CO2.
Again, the earth is an open system and without concrete causal data how can we know?
It seems like pseudoscience is taking over the planet - kind of like the "self-based morality" you see today: "I can do what I want" and now "I can believe what I want" - which is fine as long as you don't pretend that its actually science and fact.
The real reason I think that crop circles persist is that the surface of the earth on which they can be created is vast and normally its done at night in the dark - so there is only a small chance of someone coming upon the activity (and no one typically walks about in the middle of a large grain field at night).
I'd like to write more but an alien craft just landed outside in my field and I have to go...