Fans of The Hobbit may recognize one salvo from the Riddle Game. If you're not a fan of The Hobbit, it might be fun to google.
You're looking for a small, black bison tube, and it shouldn't be too hard to find.
You don't have to go up the driveway to find the cache, but I've known the property owners my entire life and they're well aware it's there.
Don't worry. Smeagol knows where the cache is.