All Stephanie Tarr knew was that she had a phone interview with the White House on Wednesday to discuss a letter she and her two sons wrote to President Obama for Presidents’ Day.

She never expected the call she got that afternoon.

“To my surprise, the man himself was on the other line,” said Tarr, of Coon Rapids.

Tarr was one of three mothers President Obama surprised this week with Mother’s Day wishes. She and her sons — Kenny, 9, and Kai, 3 — wrote to thank the members of the first family for everything they do “each day for our country and normal families like us throughout America,” a White House official said.

Tarr lives with her sons and their father. She’s a waitress at Good Day Cafe in Golden Valley. In her Presidents’ Day letter, she expressed hope that free preschool becomes law to ease the burden on the family when Kai starts attending. She also thanked Obama for his support for a minimum-wage increase in 2014.

The White House had been in touch with the family earlier in the week to set up a call, Tarr said, but she had no idea it would be with Obama. When she heard Obama introduce himself on the other line, she said her “heart started racing a million miles an hour” and a huge grin spread over her face.

“I was just in complete shock that this was happening,” Tarr said. “The whole conversation and everything around it has been surreal.”

Obama told her that being a mother is one of the toughest jobs in the world, Tarr said.

“He was very encouraging about the boys having a bright future,” she said.

The idea to write to the president came as a Christmas wish from Tarr’s mother. Instead of finding her a gift for the holiday, Tarr said her mother asked that the family do good things for other people. So they gave cards to a nursing home for Valentine’s Day. They picked up garbage for Earth Day. And they wrote a thank-you letter to Obama for Presidents’ Day.

“Well, boy, did I never think it would come to this,” said her mother, Sheri Tarr, who lives in Blaine.

Sheri Tarr said her daughter is someone who is always giving, though she doesn’t make a lot of money herself. For example, Tarr was at Aldi grocery store recently and saw an elderly man buying flowers and decided she would purchase them for him.

She thought the flowers would be $10. They were $32.

“That’s just the kind of stuff she does,” her mother said. “She’s just a beautiful person.”

Her son Kenny loves basketball and being with friends, and Kai “loves everything,” Tarr said.

When Tarr was younger, her family named their cat Tipper Gore, after the wife of former Democratic Vice President Al Gore. Now, she and her family have a cat named Sasha, named after Obama’s youngest daughter, which she mentioned in the Presidents’ Day letter.

In a personalized response to the family, Obama wrote: “Tell Sasha I say hello!”

“Good deeds don’t go unnoticed,” Tarr said. “If you do good for others, amazing things will happen.”