While visiting the Orchard Farm right after you complete the main quest with the same you can start a side quest named Hidden Booty Hunt.
It is advisable to start the quest as soon as you can, because its related to many other quests and it takes almost until the end of Fable Anniversary to complete.
There is a hidden treasure somewhere in Albion and in order to find its location you must collect six Treasure Clues.
Given the fact that most of the clues are given as rewards for various side quests it is recommended to follow the details in the next Fable Anniversary walkthrough if you dont want to miss the treasure during your playthrough.
Rewards
Money: 0
Renown: 100
Walkthrough
The hidden treasure is actually a weapon called the Frying Pan. It is a decent weapon that has augmentation slots, and it is possible to get it without collecting the clues, but in that case it will be useless. The quest starts in the Orchard Farm when you find your first clue.
To get it follow the eastern road that leads to the orchard, but stop at the gate, do not get inside the orchard. Between the stone wall and the wooden gate you can find a chest.
Open it to receive Treasure Clue 5 and to start the quest. You can acquire another clue later in the game, at the end of the Lost Trader quest.
Once you rescue the traders brother you get Treasure Clue 2 as a reward. After you complete the quest Break the Siege you can return to Knothole Glade to participate in the Archery Competition. Beat you high-score or score over 200 points to win Treasure Clue 4.
Treasure Clue 6 can be easily acquired while you are in the Windmill Hill area. All you have to do is to open the chest that is behind the windmill. During the Bounty Hunt quest you have to rescue two hostages. Your reward for saving them is Treasure Clue 1.
The final clue is Treasure Clue 3. In order to obtain it you have to defeat all five assassins in the Assassin Attacks quest. Once you have all six Treasure Clues return to the Orchard Farm. If you know the meaning of the clues you can find the spot where the treasure is buried.
Head to the barn and dig in the narrow space between the barn and the hale of bay (you must search for the spade in your inventory or assign it to a quick slot as it wont show in the left corner when you are above the treasure).
Once you have the Frying Pan dont discard it if its not powerful as your current weapon. Instead, equip it and kill a random enemy to get the Out Of The Frying Pan achievement.