On Wednesday April 15 ,2015 at the exact time of 2:08 PM I was on Martin Downs Blvd Stuart Florida traveling in an Easterly direction going to my insurance agents office.I had just passed the intersection of High Meadows and Martin Downs Blvd when I looked North and first observed what I thought was a flock of 12 to 18 birds in the far northern distance. The movement of the formation was not what you would normally see birds do. There was something about the objects that made me stop my car and tell my wife "DO YOU SEE WHAT I'M SEEING ? My wife's reply was yes I see it. I got out of my car and watched the northern sky at about a 90 degree angle. These white round objects were flying in some kind of formation but NOT making the usual turns like a flock of birds. The sky was a clear blue sky and no nearby clouds.At one point the 12 to 18 objects completely disappeared and reappeared , making right turns and reappearing in another area of the sky. Above the objects I could see a commercial plane that I would estimate to be 20,000 feet with the objects below.The objects were traveling in a SW direction and then disappeared again. I tried to get another visual but was unable to do so, they were gone. This is my 3rd observation in the past 32 years .