In the shadow of the Sangre de Cristo Mountains, New Mexico's Mora Valley harbors the ghosts of history: troubadours and soldiers, Plains Indians and settlers, families fleeing and finding home. There, more than a century ago, villagers collect scraps of paper documenting the valley's history and their identity-military records, travelers' diaries, newspaper articles, poetry, and more-and bind them into a leather portfolio known as "The Book of...