Motorists spotted the pattern on land near junction seven west bound, sparking a flurry of calls to the Shropshire Star.
Crop circles have long split opinion, with some claiming they are the work of aliens, while others claim they are the work of pranksters.
But local UFO researchers do not believe the Shropshire circle is a cryptic message from outer space.
Darren Perks, a UFO investigative researcher from Shropshire, said he was tipped off last week that the stunt was due to happen.
Mr Perks said: "I got an e-mail tip off last week from someone called 'Stuart' on July 25 that a crop circle would appear over the weekend. He claimed to be responsible for hoaxes in Wiltshire and wanted to try one near Wrekin hill."
The hoaxer explained in the e-mail that he would use a 'basic' technique and make the circles overnight and asked Mr Perks if he wanted to film it. Mr Perks said no because he disagreed with what they were doing.
He said: "I disagree with hoaxing crop circles as it is of no benefit to anyone. It's the farmer I feel sorry for because of the loss. The crop is damaged and he ultimately loses money."
Ryan Humphreys, from Shrewsbury, said: "I noticed the crop circle while travelling back to Birmingham. It's the first time I've ever seen one. I thought it was a great feature to an otherwise boring stretch of road.
"The theories about aliens creating them, to me, are nonsensical and I'm a firm believer that they're works of art imagined by creative people.
"However, if I was a farmer and someone damaged my crops, I wouldn't be happy. I guess there's a debate about the fine line between art and vandalism."
Lee Perry, media adviser for the National Farmers' Union said: "Creating crop circles on farmland is unfair and irresponsible – crop circlers always seem to forget that they are damaging someone's property."