Going Mad or an Optical Illusion

Today's May word challenge is Mad. I had no idea what I could blip until I walked to the next village to try to catch a sunset by the lake. On the way I thought I was going mad. This field looked out of focus. I blinked a couple of times but it remained blurry. As I looked around I saw that the foreground and background were ok and I realised it was an optical illusion in the field of wheat!