One woman's secret Santa this holiday season turned out to be one of the richest men in the world: Microsoft co-founder Bill Gates.

The gift exchange happened through the social website Reddit's secret Santa event, in which users swap presents across the country.

The woman, identified only as Rachel, wrote in a blog post that she was first surprised to find out that her gift was a 7-pound package that was being overnighted.

Inside the package, Rachel found a stuffed cow toy, a National Geographic travel book, a donation to Heifer International in her name, and a card signed "to Rachel, from bill," according to the post.

It was only when she found the travel book that she discovered a photo of the billionaire philanthropist holding the gifts that were in the package, Rachel wrote in her post.

Gates spokesman John Pinette confirmed Gates participated. Gates wanted to engage with Reddit's community and promote Heifer International, a foundation that provides seeds and animals to people in need in the developing world, he said.

The foundation also provides education to youth in impoverished nations, according to its website.

Rachel was especially happy to hear about her contribution to Heifer International

"The last part was/is my favorite, since my master's degree is in education and I am SO into educational benefits for all," Rachel wrote in the post. "It makes me so happy that he was able to donate to a charity on my behalf that helped people with both needs and educational benefits. Nailed it, Bill!"