Wildlife Spotting

There's a good chance that these are Killdeer (Charadrius vociferus) eggs: http://en.wikipedia.org/wiki/Killdeer Killdeer nest on the ground in flat areas, often on flat roofs, fields and I would imagine on the edge of parking lots as well. I am not absolutely certain. If you were that close to the nest, the parent bird shouldn't have been too far away. They have a distinct call that you might have heard if the bird was flying around above you or standing nearby. There is a recording of the bird call on the Wikipedia page I linked to.