Someone in St Paul is going around putting $300 cash in people's mailboxes

The bills appear to be brand new straight from bank so I think some wealthy person is behind this. The wealthy person took out a lot of new $100 bills from bank and put them in envelope with a preprinted "have a good day" message in letter. So that wealthy person did a lot of these letter prints and envelopes but the address on the envelope appears to be handwritten.