I had a book on Tolkien's languages -- ah, this: The Languages of Tolkien's Middle Earth by Ruth S. Noel that I studied earnestly through high school, learning Quenya and runes and everything I could.

I've since seen people talking on the interwebs about how that was basically a crap book, but whatever, it made my nerdy little high-school LOTR-loving heart happy.

Origin stories are the best!