English: Unexpected Wealth

I was watching TV shows when my mom yelled out 'go clean out the garage!', I didn't want to do it but my mom was screaming at me so I had no choice but to do it. I was cleaning all sides of the garage and then I found an old shoebox in the back corner. It was a lot heavier than I thought so I started wondering what inside, I opened it and saw a lot of money inside. I counted it and it was 40,000$ cash to be exact, I wondered where it came from or who. I was also wondering why the owner of the money left it there in the garage.