White boomerang shaped objects swarming and floating then immediately disappeared together.

Looked West into sky at 11:30 a.m. today and noticed what I thought was a flock of white birds.  Their movement wasn't bird-like and they didn't form into any sort of distinct patterns together.  The way they moved seemed as if in all directions including backwards and sideways and they sort of swarmed around like kites but independent of anything holding them.  They were all white and shaped like boomerangs and kept moving in a swarm and all of a sudden simply disappeared.  My friend and I both watched them trying to figure out what they could be.  No idea.  As for background, I have no scientific training and we were simply standing out by my car.  I wish I had thought to take a photo.