A crop "circle" is a geometric pattern, often very intricate and complex, appearing in fields, usually wheat fields and usually in England. Most, if not all, crop circles are probably due to pranksters. For example, Doug Bower and David Chorley admit to hoaxing approximately 250 circles over many years.
Some believe that the crop designs are messages from alien spacecraft. Some maintain that the aliens are trying to communicate with us using ancient Sumerian symbols or symbolic representations of alien DNA. Those who engage in such serious study and theorizing about crop circles are known as cerealogists (after Ceres, the Roman goddess of agriculture and fertility) or croppies.
Crop Circles can range in size from only a few feet across to several hundred feet in diameter. Sometimes larger designs are accompanied by a smattering of tiny circles (some barely a foot in diameter) these are referred to as 'grapeshot' or 'satellite' circles. One of the largest designs recorded appeared at Milk Hill, in Wiltshire, it measured over 900ft in diameter and the design was made from 409 circles all arranged in a circular spiral. The 409 circles circles in the formation ranged in size from 70ft down to about a foot in diameter! However, all this said, the average size for a crop circle is around 200-300ft in diameter - still no small feet!