Large apparently disk shipped object moving in circular motion about 75-150 feet in the air.

About 8:00 pm at night after, picking up pizza for dinner, my daughter in law was driving west on highway 250 towards Sumner, Illinois from Bridgeport , Illinois. As she approached the turn off for Hopewell cemetery she noticed unusually bright lights in the field to her right. Slowing down to get a better view of the phenomenon, she was shocked and shaken when she realized that it was a very large disk shaped object 75-150 feet in diameter slowly moving in a circular pattern around the north end of the open field. The object had a dark surface and was ringed by multicolored lights around the periphery of said object. The disk-like shape was only discernible because of the lights around the outer edge. The object was moving just above the tree-line. The lights around the edge were moving in a fixed pattern around the object. She described the motion of the lights as the motion of chasing lights on a theater or advertising marquee.
Until the moment of her sighting she was a hardcore skeptic. When she called us to relate her sighting, she was very shaken and displayed a reaction of someone who has just had their perception of reality destroyed.
She slowed down observed the object intently enough that she totally forgot to control the car she was driving. She crossed the centerline and ran off the shoulder of the road before regaining control. According to her, the near accident snapped her back to her senses and in a panic she sped away. It was only when she reached the safety of her own home that she realized that she was so shaken by the experience that she completely forgot to take pictures.