The cards turned out to be Exodia the Forbidden One, Right Arm of the Forbidden One, Right Leg of the Forbidden One, Left Leg of the Forbidden One, and Left Arm of the Forbidden One.
Fishing them out of the water, he ended up with five cards, and not just any five cards either.
Or, maybe this really was just a real-world manifestation of the heart of the cards, and @KONBUmaster is destined to become the greatest Yu-Gi-Oh! duelist of all time.
However, Weevil threw the set into the ocean, not a river, so it appears that the cards @KONBUmaster discovered were not, in fact, Yugi’s.