"Later! Yes, when you also have the Keys of Barad-dûr itself, I suppose; and the crowns of seven kings, and the rods of the Five Wizards, and have purchased yourself a pair of boots many sizes larger than those that you wear now..." -Saruman (to Gandalf);The Two Towers
The seven crowns probably refer to the crowns of the Seven Tribes of the Khazâd:
- The Crown of Belegost (Firebeards)
- The Crown of Gamil-Nala (Ironfists)
- The Crown of Kibil-Tarag (Stiffbeards)
- The Crown of Moria (Longbeards)
- The Crown of Nargubraz (Blacklocks)
- The Crown of Nogrod (Broadbeams)
- The Crown of Ruuriik (Stonefoots)