How many games with in-game card games (think we've said 'game' enough yet?) do you know of that tell you all of the possible rewards up front? Most of them keep it a mystery to not only leave it as a surprise, but also to pad your playtime unless the game goes out of its way to tell you when you've received everything possible.

If you care that much, like Jeycht points out there are plenty of third party fan sites that list possible NPC rewards so just use one of those.