♪ money changes everything >> yeah, it does change everything, money does. >> uh-huh. >> people in san francisco know that because they have been finding cold, hard cash in random places all over town. >> that's right. the money stashed by a man who says he's been lucky and he wants to encourage others to give as well. so abc's nick watt tracked this mystery donor down. >> reporter: san francisco is going gaga for green backs. a mysterious millionaire is stashing cash around the city and tweeting clues like this -- find me at the highest point in the park under a place for dog owners. from that, samantha found 100 bucks in a dog dirt bag dispenser. >> my hands were shaking and i ran down the hill to find my fiance. >> reporter: thousands of treasure hunters await every new