For some reason once I finish the part where you get your first rune and your blink power, about 10 bone charms along with some statuettes (the ones that increase your max bone charms) appear in Corvo's room. Is this a known bug? This is happening on a fresh save file.
if you preordered Dishonored with 'Arkcane Assassin Pack' (from Gamestop) and/or 'Back Street Butcher Pack' (from Amazon), you get access to 6 special bone charms, available in Corvo's room.
Void Channel: Corvo's supernatural abilities last longer and do more damage Gutter Feast: When Corvo eats a white rat, he regains mana. White Rat Friend: White rats are neutral towards Corvo, not hostile. Fencer: Win sword vs. sword contest more frequently. Blast Resistant: Damage from explosions reduced slightly. Fire Water: Shot whiskey bottles explode with greater intensity.
source : IGN
just found out about some other charms that appear in Corvo's bedroom HERE.