Flat circular cloud formation falling from the sky as if heavy then hovering

This occurred in Hadley Massachusetts. I saw a huge circluar flat disk that looked like a light gray cloud, slightly darker than the sky.
It seemed to be falling from the upper atmosphere the way a paper plate might spin if dropped from up high.It was as if this unusual cloud formation had weight unlike a whispy cloud. Never hitting the ground it leveled, off hovering, like a huge oval rounded at the top flatter on the bottom, no longer looking flat.
I was in the cornfields behind the Connecticut River known as the "Honey Pot" (dirt road area). The object was east to slightly Northeast seemed to be above UMass Amherst area. It was at a 45 degree angle from where I was less than a mile up (even though it had several hundred feet higher up) and easily 4 miles away. I have never seen such a thing in my life.
Although I made my friend pull the car over he couldn't see it. It happend so fast, then it just faded into the gray sky.