Crop circles, mysterious patterns that seem to occur in wheat fields overnight, have been the subject of fascination for centuries. Explanations ranging from demons to space aliens have been posited over the years. Why demons or aliens would do such a thing is a matter of conjecture.
The crop circle phenomenon has been the subject of TV and movies, most notably "Signs," a film by M. Night Shyamalan, starring Mel Gibson.
Crop circles are more often than not the work of human beings, either openly as a form of art, or clandestinely as a hoax. The standard technique is somewhat pain staking, using planks and rope to flatten crops to create intricate patterns.
But according to Professor Richard Taylor, director of the Materials Science Institute at the University of Oregon, crop circles are being created using magnetrons which are commonly found in microwave ovens. Very likely GPS transponders and lasers are also being used to exactly create patterns in wheat fields
This method allows hoaxers to do their work under cover of darkness, in a single night, and to be away before being discovered. Farmers and other people coming upon the crop patterns are left to wonder how they came to be.
Though it has been demonstrated, as related in an article in Scientific America, that human beings can create crop circles using even the traditional simple plank and rope method, the will to believe in some kind of supernatural agency is still very strong. The slogan often used on the TV program "The X Files," which states "I Want to Believe" articulates the tendency succinctly.
Still the idea that groups of hoaxers, who clearly have too much time on their hands, are doing this just for their own amusement is a compelling enough story without bringing in artistically minded aliens. Perhaps someone could make a movie based on that premise as well.