The bizarre patterns are attributed to everything from freak weather to unidentified flying objects to hoaxers.
Over the past two decades the circles have spawned a mini-industry of talks, books, and tours. And now you can take the college course.
This autumn Swindon College is running a one-day course given by Jude Stammers, an Oxford-
educated scientist and expert on mystic sites.
It is a serious attempt to study the circles, says Avril Carlton, Swindon College's head of community education.
"We're not being flippant about it," she said. "The tutor is an astrophysicist who takes the subject very seriously. Although there are people wanting to do traditional things like cookery, we are always looking for new subjects.
"We try to pick up on local issues and this is a big local issue. There's a lot of interest."
Ms Stammers, currently on a lecture tour in the United States, said the course will explore the history of the circls and include her theories on their origins.
She believes they are not man-made, and that the often-complex geometric patterns carry some kind of message for humanity to decipher.
"I have lived in the Avebury area of Wiltshire, which is at the centre of the phenomenon, for six years. I have been very much involved.
"The course will cover some of the history of crop circles, and some of the current research into how they're formed. But more than that, I really want to explore the reasons behind it."
The course has been welcomed by the 350-member Wiltshire Crop Circle Study Group, which photographs and documents the circles.
Spokeswoman Francine Blake said 55 crop circles have been found in Wiltshire this summer and despite claims of hoaxes, there has been a resurgence of interest in them.
"Our belief is that there's something very important going on and we're studying it," she said. "There's still a huge interest."
The one-day course takes place at the Natural Health Centre in Marlborough, Wiltshire, on November 4.