Giant black circular object peeping in and out of back of weird Grey storm cloud

I was looking up at the dark cloud that brought with it rain and thunder from an otherwise clear blue hot day.The cloud came in like a tornado almost, and also brought brief strong winds with it as it came towards my home, and then peculiarly enough changed direction and headed eastbound. This cloud was moving faster then I had ever witnessed any cloud ever go before. So as I'm watching hang the tail end of the cloud accelerating east and almost out of sight for me standing in my backyard watching it. A black circular (I don't know what) appeared from the back of the cloud. It had to have been pretty big if I could see it so well and it being that far away. It behaved almost like a giant balloon would. But obviously it could not have been a balloon. It came out of the back of the weird storm cloud and went up and then floated down and the a little more up and then a little more down before I could no longer see from over my neighbors homes. It looked like a ! perfect circular object and it seemed to be using the cloud to disguise itself as it hovered on through the sky. The sky went back to clear blue right after the cloud passed by and it was a very strange. And also, the birds were all acting very strange and flying very close to me and my daughter or letting us get very close to them which is not normal behavior for birds.