Hide it at least 3 miles from your home, take some pics and tiny sample for proof. Call that shady guy you know who married your cousin (use cheap prepaid phone if you're feeling extra nervous). Tell him his guys can have it for $100k if they bring the cash in 3 hours, otherwise you're calling five-oh anonymously so they can get it instead. Shady guy brings cash, you show him pics and sample, get cash, and give him address. Deposit $80k in credit union CD and go on vacation for two weeks in Monaco. Wash hands of the whole thing.
Edit: Oh, and burn the clothes you wore and have your vehicle professionally cleaned from top to bottom.