There are several groups of people who have claimed to have made all crop circles. The first of these were the "famous" Doug Bower and Dave Chorely who, in the early 1990's made a belated career and a fair bit of money from their claims that they were the sole creators of crop circles. They claimed to have begun this work somewhere around 1978 and continued to make dozens fo crop cirlces every year, all over the world, for more than a decade before "revealing" their cunning hoax.
A number or reputable people have examined the claims of Doug and Dave and proved that they were lieing. The best, and most complete, examination of their claims comes from Terry Wilson on his website Old Crop Circles "The Men Who Conned the World"
The Circle Makers
Possibly seeing the fame, fortune and notority achieved by Doug and Dave other hoaxers appear to have decided to 'cash in' on the international interest in crop circles. These artists (in Australia we would call them bullshit artists) also claimed to have been responible for making most or all of the crop circles appearing in Britain. Indeed as soon as a crop circle received any media coverage these 'circle makers' would claim to have made it.
The circle makers appear to be led by artist Rod Dickinson in conjunction with web site designer John Lundburg and a supposedly "secret team of collaborators" who descend on grain fields in the south of England during the short summer nights and create crop circles using nothing more than “string, simple wooden planks and an outline of their design”. There is no evidential support for the circle makers' claims and, in fact, to accept them one must ignore a large body of published work, facts on crop circles, that challenge the circle maker’s claims. For example Dickinson claims to have been responsible for the creation of a famous 200 metre long crop circle known as the Double Helix, which appeared in Alton Barnes in 1996 and which pattern contained 89 separate circles. However the facts on this crop circle appear in a news piece published in the highly respected scince journal Nature Vol. 382 July 1996 wherein the farmer who owned the land upon which the circles appeared stated that the formation appeared some time between midnight and 4 a.m. in the morning. This means that Dickinson had less than four hours to create this massive 200 meter long series of crop circles, which contained 89 separate circles arranged in an extremely precise manner, without leaving any trace of his group’s coming and going, despite the field being close to the farmer's residence.