Michigan woman's Secret Santa is Microsoft co-founder Bill Gates

A Michigan woman recently discovered that her Secret Santa on an online gift-exchange platform was none other than Microsoft co-founder Bill Gates.

The Detroit woman, Shelby, who preferred not to use her last name, participated in 95 RedditGifts exchanges, an online user-to-user gift exchange, before receiving her surprise from the billionaire on Dec. 18, according to her Reddit post.

She told FOX Business she has been participating in the gift exchange since about 2013, the same year Gates, coincidentally started participating, according to tech news site Geek Wire.

"The generosity of his time meant a lot to me, and it meant a lot that he would take the time out of his day to do this for me because I'm sure he's a very busy person," Shelby told FOX Business.

She explained that she joined RedditGifts because she wanted to spread happiness to people online from all over the country that she "would have never otherwise met."

Gates sent Shelby an enormous box full of gifts, but most generous of all was a donation to the American Heart Association in the name of Shelby's mother, who passed away 10 days before her wedding.

Her mother's death was a shock because she was not sick, Shelby told FOX Business, adding that her family chose AHA as their charity of choice for her mother.

"Bill Gates, you are a blessing," she wrote on Reddit. "This year has been a complete rollercoaster of emotions for me; in March, I lost my mother completely unexpectedly only 10 days before my destination wedding. It has been hard to drum up holiday spirit this year, and this has been a zap taser of Christmas cheer."

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Before receiving the package, Shelby tracked it and noticed that the gift was shipped overnight from Washington state and joked with her husband about the gifter being Gates. The next day on Dec. 18, she tracked the package again to make sure it was still on its way and noticed that the shipment weight 81 pounds, she said.

"I have felt like I’ve been on another planet the past few days, and I still cannot believe how lucky/cool/honored/all the adjectives I am to have had someone craft such a special and personal set of gifts just for little ol' me," she wrote on Reddit. "And your donation to The American Heart Association in my mom’s memory is the most special gift of all. It means more to me than I can express."

Shelby told FOX Business that she and her husband were texting back and forth after she found out how much the package weighed.

"We just couldn't believe it," she said. "We thought maybe it was a mistake. Was the package actually 8.1 pounds and not 81 pounds?"

Gifts inside the box, which was illuminated by Christmas lights on the inside, appeared to be personalized to Shelby's tastes.

They included Bill’s Deck of Books 2019, a "Harry Potter" Santa-style hat, Hylian shield earrings, a handmade Legend of Zelda-themed quilt, a hammock with a bug net, almond roca candies, Seattle mint chocolates, Jelly Belly jellybeans, cat toys, seven packages of assorted Oreos, a cat-themed logic game, eight hardcover books, a manuscript copy of "The Great Gatsby," a candle with a "Great Gatsby" inscription, two adult LEGO sets and a number of "Twin Peaks"-themed gifts, according to the post.

Shelby said to pay Gates' kindness forward, she is going to continue participating in RedditGifts and will use some of the wrapping paper that Gates used for her gift to wrap her gifts to other Reddit users.