A crop circle (or a crop formation) is a sizable pattern created by the flattening of a crop. The documented cases have substantially increased from the 1970s to current times. Twenty-six countries reported approximately ten thousand crop circles in the last third of the 20th century. Ninety percent of those were located in southern England. Many of the formations appearing in that area are positioned near ancient monuments, such as Stonehenge.

Possible explanations include: man-made, weather, paranormal, animal activity, extraterrestrial activity. While some cases are clearly man-made and known to be a hoax, others present evidence that is difficult to explain. In some examples the plant stems are elongated and bent yet undamaged, some crops exhibit blown nodes, stunted seed-heads, cell wall pit enlargement, and expulsion cavities.

In 1995, a five-pointed star appeared at composer Andrew Lloyd Webber’s country residence at Kingsclere, despite the property being manned by a 24-hour security team. With the extensive grounds rigged with sensors and microphones, a research team looking for the pictogram was apprehended within minutes of their arrival. No one had been caught making the pattern. Webber was on holiday at the time and his security staff rang to tell him what had happened. Convinced that all crop circles were fakes, he was furious and demanded to know how the hoaxers had gotten in unnoticed. When he was told that it seemed there had not been any hoaxers, he reportedly burst in to tears.