The Hoarder achievement in Fable 2 is worth 25 points and can be unlocked by obtaining all 50 silver keys or seeing another Hero do so.Xbox 360 Achievements: Fable 2 Achievements

Silver Keys can be found in various locations across Albion including caves, houses and dig spots. Each one that is acquired by the player gives them access to another chest. Each chest displays a number that corresponds with the amount of keys a players must in order to open it.

To check how many keys are in your area, bring up the in-game map and look towards the bottom. There should be a section that keeps track of this information as well as the amount of Gargoyles that have been destroyed.

Additionally, players are strongly advised to visit the book store in Bowerstone. There, you can train your dog to sniff out treasure so that it can alert you to any special items that are nearby.Xboxer360.com: Fable II Achievement Guide