Looks like Mr. No Shoulders has outgrown his clothes and gotten himself a new suit!
He's gone, but rest assured, he's not forgotten. I'm pretty sure this came from a 3 foot Rat Snake (we have plenty of those around in the woods), but we also have Copperheads (seen plenty) and probably Rattlesnakes (not seen one on my property yet).
Needless to say, I'm very cautious when I walk around outside in the dark! Even Mr. Rat Snake could make me hurt myself trying to get away.