Source: Tales from the Yawning Portal

Wondrous item, rare

The holder of this platinum hand mirror can learn something about the history of a specific object or creature by taking an action to gaze into the mirror and think of the target. Instead of the holder's reflection, the mirror presents scenes from the target's past. Information conveyed is accurate, but it is random and cryptic, and presented in no particular order. Once it is activated, the mirror gives its information for 1 minute or less, then returns to normal. It can't be used again until the next dawn.