Crowns of Seven Kings

In the book The Two Towers, Saruman quotes to Gandalf: "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..."

There has always been a mystery to who the Seven Crowns belonged to. Given the context of Saruman's speech--he is stating that Gandalf wants control over everything, making Gandalf out to be a villain more than he. With that stated, Saruman referred to himself, Gandalf, Radagast, Alatar, and Pallando when he made the statement about the Rods of the Five Wizards. But the Crowns of Seven Kings have always been a mystery.

Given the relevancy of Saruman's statement, it is befitting to note that the Crowns are of Seven Kings who are alive in Middle Earth at this time given that Saruman and Sauron represent the keys, the Istari for the Wizards--so the Crowns have to be just as relevant as these other statements is therefore referring to seven kingdoms that oppose Saruman and Sauron, the "Free People's Kingdoms of Middle Earth" if you will.

So the Crowns of Seven Kings is as follows:

Crown of Gondor: Aragorn II

Crown of Dale: Brand

Crown of Mirkwood: Thranduil

Crown of Erebor: Dain II

Crown of Rohan: Theoden

Crown of Bladorthin's Kingdom, possibly Dorwinion: Unknown

Crown of some Unknown Free People's Kingdom in the South or East: Unknown