Looks like Laine doesn't see much worth in what you've found. "Nice find, rookie," says Laine. "I think I have a stack of these back on my desk in Stormwind City. We're basically at square one here. All we know is...someone who likes to write fiction about the past sent the Furlbrows a letter. Looks like we got ourselves a real history...mystery."
Ask what Laine thinks you should do. Maybe he actually has an idea. Check for clues on your own. Laine seems stumped. You can do better. Ask if anyone here knows someone who knows about this past that the "fiction" might be about. That might give a clue.