Crop circles are a world wide phenomenon, having been reported in virtually every country around the world (all except China and South Africa), They are usually based around a circle (but not always) and can be extremely elaborate in design.  Usually occurring throughout Spring and Summer, crop circles have gained mass public attention since the 1960's, however there are documented reports of crop circles dating back to 1686. 

Crop circles are also known as 'Saucer nests', and are thought by some to be the marks left by UFO's upon landing.  Crop circles are varied in both size and complexity with some of the most elaborate designs having been found in the United Kingdom.

Another theory is that the crop circles are messages left by an alien race attempting to communicate with us, another still suggests that they are messages of warning from 'Gaia' the spirit of the Earth also known as 'the Earth mother'. 

Others of course believe crop circles to be the work of hoaxers or the results of  government experiments using lasers fired from outer-space.

In the UK two old men admitted to having created all or most of the crop circles, however demonstrations they gave to the press to prove this, produced crop circles far inferior in quality and complexity then those for which they took credit.