These are osteoderms, the boney armor, of a very large alligator. I believe these to be laterals from the neck or back based on the articulating edges. These are the most impressive examples I have come across in Florida. The example on the left in the image is 3.35" wide and 2.48" long at the central boss. Pleistocene of Volusia County, Florida.
(This image is best viewed by clicking on the "options" button on the upper right of this page => "view all sizes" => "large".)