According to the following DailyMail article, the first proper crop circle of the season sprouted in Wiltshire, UK.

The 100 foot circle was discovered overnight in a field of oil seed rape. No information given if there will be a follow up investigation, but I don’t doubt that some Ufologist is already at the site taking samples.
Although a lot of the crop circles have been debunked as hoaxes or art projects, there are still those that remain unexplained. Those are the circles that appear over night, at times within only a few hours, and there are the ones that appeared centuries ago. The phenomena is not new.

The unseasonably warm spring weather has not only brought forward many summer flowers – it has sparked the usual round of crop circles.

An elaborate 100ft circle which appeared overnight has caused a stir after it was found in a field of oil seed rape near Silbury Hill, Wiltshire.

The extraordinary floral creation is comprised of six interlocking ‘petal’ like crescents.

The ancient site, the tallest prehistoric man-made mound in Europe, is considered a hot spot for the bizarre phenomena and this new design proves the crop circle season is now under way.

Expert Lucy Pringle, widely known as an international authority on crop circles, believes this is the first ‘proper’ design of the year.

She added: ‘The start of the season is always exciting, I never know what’s going to happen for the rest of the year.

‘The latest circle is a floral pattern, I’ve never seen this before. There’s never been one identical to another.’

Miss Pringle, from Petersfield, Hants, is a founder member of the Centre for Crop Circle Studies.

She has conducted years of research in to the physiological and psychological effects reported by people after visiting the formations.

She says her findings suggest there are measured changes in human hormones and brain activity following contact with the circles.

The new ‘floral’ design is the latest in a long line of patterns to be spotted in the UK over the years.

Previous formations have included stars, triangles, birds, complicated three dimensional geometric shapes and even intricate patterns with hidden mathematical codes.

One, discovered in 2008 near Wroughton in Wiltshire, was thought to represent the first ten digits of pi, the ratio of the circumference of a circle to its diameter.