At least five formations appeared during the weekend, one each in Lincolnshire (home county of Matthew Flinders who figures in our local history in South Australia), Somerset, and the rest in Wiltshire.
In one, the first visitor reported that his camera refused to work within the formation, but had no problem taking the image from a nearby vantage point.
Another is described as "very delicate and cute", having great precision. At least one crop was harvested within hours by the farmer, which of course removes the formation.
These pages from CC Connector - which you are invited to visit and join - will tell you more, regardless of what you believe about this phenomenon: