Thank you for all of your comments and participation.
The winner is D. Nash of the blog "My Leaky Waders." His submission of Heterodon platirhinos was the first 100% correct answer. The snake is indeed an Eastern Hognose (H. platirhinos).
Ty got us started on the right track, but there are three species of hognose snakes in the U.S. so I asked for a more specific answer.
Ivan was close with Southern Hognose (H. simus), but they're actually quite rare these days- especially in Mississippi.
The real giveaway for this snake was the unique morphology- the unmistakable upturned snout and short stout body of a hognose snake. The question then becomes which of the three U.S. species could it be? The Western Hognose (H. nasicus) is not found in Mississippi. The Eastern and Southern species are both found in Mississippi, but the Southern species is only found in the southeastern portion of the state. Southern Hognose Snakes have actually become quite a rare find. In the hints I gave, I let you know the snake came from central Mississippi. The only hognose snake found there is the Eastern Hognose. The head pattern is still quite typical of an Eastern Hognose. You can check out some photos by clicking here. You'll also notice that Eastern Hognose Snakes are commonly found in a melanistic black phase.
David, send me an e-mail at firstname.lastname@example.org with your mailing address, and let me know which prize you would like to claim.
Thanks again to all who participated in my first ever blog contest.