From
http://forums.projectego.net/devalions-fable-faq-1566/
Q: How many treasure clues are there?
A: There are 6 treasure clues in all.
Treasure clue 5: This is in Orchard Farm, in the left side area. Open the chest
to find the clue.
Treasure clue 2: Finish the "Lost Trader" quest*
Treasure clue 4: Complete the Knothole Glade archery competition
Treasure clue 6: Find at Windmill Hill
Treasure clue 1: Complete the "Bounty Hunt" quest*
*These quests you will find at the Heroes Guild throughout the game
To get the last clue, you need to do the Assassin Attacks quest. After doing the
"White Balverine" and "Break the siege" quests you will be told by the
Guildmaster that assassins are after you. You will find them at Knothole Glade,
Witchwood Cullis Gate (Focus Site, big rock coming out of the ground), Windmill
Hill, the Prison Path, and Hook Coast. Kill them all, and the last one you kill
will drop the Treasure Clue 3.