What Came From the Stars by Gary D. Schmidt
From Publisher's Weekly: "In his new novel, Schmidt (Okay for Now) shifts from historical fiction into out-and-out fantasy. Tommy Pepper lives in Plymouth, Mass., where his mother's recent death has shell-shocked his small family. Meanwhile, in a far-off galaxy, an epic battle between good and evil has reached its apex. To save the most important aspect of his culture, Young Waeglim forges the 'last of the Art of the Valorim' into a chain and hurls it into space, where it streaks past comets and stars before landing in Tommy's lunchbox. He puts it around his neck, and special powers ensue. Tommy's chapters are vintage Schmidt, with improbably named characters, authentic (and funny) classroom dynamics, and his familiar stylistic tics of referring to characters by both first and last names and frequently repeating key phrases."