The donor has been conducting the Northern California treasure hunt by posting clues to a Twitter account called HiddenCash, sending followers to uncover envelopes filled with about $100 taped behind stop signs, bulldozers, fire hydrants and dumpsters.
By late Wednesday, more than 190,000 people were following the Twitter account.
The donor describes the five-day-old game as way to give back to society after making millions in the city's real estate market.
"I want the spotlight on what I'm doing and trying to do," he told CNN. "I have no plans to stop anytime soon. I'm planning to continue this indefinitely into the future."
The donor has encouraged winners to tweet photos of their winnings. So far, the experiment has appeared to be a success.
A local television web producer treated co-workers to pizza, while another donated the cash to San Francisco's St Anne's church and another to the Muttville Senior Dog Rescue, according to postings on Twitter.
Web Producer Adam found @HiddenCash on Friday, bought pizza for the newsroom today! Thanks, man! pic.twitter.com/NQZwqELa4b
— KGO 810 (@KGO810) May 27, 2014
Deidre Washington, 35, of Oakland, said in a phone interview that she and her 14-year-old daughter used a Twitter clue to hunt down an envelope taped to a parking meter in San Francisco's Mission district with $60 inside.
Washington said she split the contents with several homeless people at a camp nearby. "We're always trying to give back," she said.
The pair then doubled their winnings after following a second tweet to another $60 envelope at Burger King.
"We split it - she's using it for the summer and I got some gas," Washington said of herself and her daughter.
"Hiddencash is NOT instead of charity," the donor tweeted on Monday. "We support many charities too. This is for fun."
Though the game began in San Francisco, envelopes have begun appearing in Oakland and San Jose.
Alex Doxie found the first envelope in San Jose on Wednesday - $120 attached to a fire hydrant, according to a local media report.
"I’m going to take my wife out to dinner,” he told local news station KTVU.
The donor does not plan to keep the game confined to northern California, saying on Twitter that Los Angeles residents will soon get a chance to treasure hunt their own envelopes of cash.
COMMENTS (3)
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ
@zubair: Are you serious with what you just posted? Sharing your wealth with the society is waste of time? And this shows the glimpse of US economy? Hail your analysis man! No matter what this anonyms guy intends or how he makes money... he is giving it away which needs some effort. Only if we could start giving out charity to balance the economic conditions in our own country before we raise finger on others to satisfy ourselves.
A great example of sharing the wealth and giving back to the society without using name. God has not blessed the US for nothing.
Whether its a hoax or not, shows a glimpse of US economy. People are willing to waste hours of their time.