I am not licensed in your state but in many states, the Sheriffs office will serve civil papers like lawsuit complaints and summons, small claims etc. This sounds like it might be a lawsuit but no way of telling for sure.
Take these papers to a local IA lawyer asap because service of papers might well mean you are being sued. Such official activities by the local sherriff includes service of process for complaints at law, at equity, and summons for same.
Since you are in SC it's difficult to see how Mr. Brinkmeier's advice to take it to a local IA lawyer is going to help much. Follow the advice of my other colleague. The most important paper a sheriff is likely to serve on you is a summons and a close second is a notice to appear. Pay attention.