A Nest

I found this nest on the ground today. I was walking past when a bird flew up only a few feet from me, and I thought that since it waited until the last second to fly away, it must have been guarding a nest, and it was. I didn't get a good look at the bird, but it had a brown back and was about the size of a robin. I think it might have been some kind of thrush, but since these eggs aren't blue, maybe it is sitting on brown-headed cowbird eggs. Does anybody know whose eggs these are?

May 21 I saw the bird today and it is a brown thrasher. Just to let you know.