She was treating her friends to the contents of her back pack. But it wasn't books. It was paper... paper money, that is. And lots of it! $100 bills, amounting to $20,000! Where had she gotten so much cash? Oh, from a kid across the street - who had gotten it from her parents without their knowledge.
All the money was eventually recovered and returned to the parents of the neighbor child, who claimed the money with embarrassment.