What is the biggest amount of money

$700 dollars in an envelope. There was a a name on the envelope so I returned it. They gave me $50.

Does finding wallets count? I found a wallet just last month. A few years ago I found a pouch with what had to be hundreds of euros sitting in a super market shelf.

I stuck around for a little bit expecting for someone looking for it and sure enough, an old lady in distress appeared. Glad I made someone's day that day

20 bucks.

I found someone's phone a couple of years ago, they left it on their trunk. I picked it up and waited for them to come back out of the store. Their were pleasantly surprised someone hadn't taken it.

I just remembered another similar story but it doesn't involve money.
I was staying with my grandparents and had went out for my nightly run. I saw some debris on the sidewalk and just jumped over it. Right there was a credit card. I stopped to take a closer look and there were papers and cancelled checks along with a phone card. I brought it home. In those days, the first 10 digits on a phone card were the customer's phone number so we called them.
A man and woman showed up about an hour later and asked me to show them where I found it. We walked about 1/4 mile along the road and found all sorts of papers. Apparently someone had stolen her briefcase. Best guess is whoever had done it had busted the briefcase open and chucked things from their car window and drove along as they went through it.
Then we found this black notebook. The woman went crazy when we found that. The notebook was her company ledger, it included customer numbers, suppliers, accounts, transactions, receipts. She said I had saved her business . She gave me $40, then I found out her husband gave my grandmother another $60. So I took my grandparents out for dinner that night.