Anyone who knows Cindy Brinker Simmons knows just how hard it is for her to keep a secret.

And the daughter of two late legends — tennis phenomenon Maureen “Little Mo” Connolly and restaurateur extraordinaire Norman Brinker — has been keeping a big one since 2015.

That’s when she learned that the U.S. Postal Service was going to honor her mom with a commemorative “Little Mo” stamp.

It took four years, mountains of legal documentation, hundreds of hours of conference calls, thousands of emails, unaccustomed patience and silence.

But last week, her Energizer Bunny efforts finally paid off when the postal service announced that it will honor Connolly Brinker as “an American treasure and historic sports figure” when it issues its “Little Mo” Forever stamp nationwide on April 23.

“Quite candidly, the hardest part of this beautiful project has been the confidentiality,” says the 61-year-old public relations veteran and author. “It’s not easy for anybody, and for Cindy Brinker Simmons,” she says of herself, “it’s very difficult. You can imagine, four years!”

Her mother was a 5-foot-4-inch dynamo who captured the hearts of the tennis world and beyond as a teenage phenom who won nine Grand Slam tournaments in three years.

Think Tiger Woods and Jordan Spieth, only much younger.

Maureen, quickly dubbed “Little Mo,” won all four Grand Slam titles — the Australian Championships, the French Championships, Wimbledon and the U.S. Open — in 1953 when she was just 18. She was the first “woman” do so in a calendar year.

A shooting star

Little Mo’s career was tragically cut short the next year when she and the horse she was riding were hit by a cement truck. Her leg was injured, but she stayed active in the tennis world until she died in 1969 at 34 after a three-year battle with ovarian cancer. This year marks the 50th anniversary of her death.

So her eldest of two daughters was thrilled when, exactly four years ago, the postal service contacted the Maureen Connolly Brinker Tennis Foundation out of the blue to say that it would be issuing a Little Mo stamp.

1 / 2Cindy Brinker Simmons poses for a portrait with the design for a U.S. Postal Service stamp honoring her mother, Maureen Connolly-Brinker, on Thursday, January 31, 2019 at her home in Dallas. Maureen Connolly-Brinker, known as "Little Mo," won nine Grand Slam singles tennis titles in the early 1950s. In 1953, she became the first woman to win all four Grand Slam tournaments during the same calendar year.(Ashley Landis/The Dallas Morning News)(Ashley Landis / Staff Photographer) 2 / 2Photos of and trophies won by Maureen Connolly-Brinker are displayed in the home of her daughter, Cindy Brinker Simmons, on Thursday, January 31, 2019 at her home in Dallas. Brinker Simmons has been working to honor her mother with a U.S. Postal Service stamp. Maureen Connolly-Brinker, known as "Little Mo," won nine Grand Slam singles tennis titles in the early 1950s. In 1953, she became the first woman to win all four Grand Slam tournaments during the same calendar year.(Ashley Landis/The Dallas Morning News)(Ashley Landis / Staff Photographer)

“Mom’s career was very short and meteoric — from 1951 to 1954,” says Brinker Simmons. “We’re talking 65 years ago. I’m so touched that, of all the tennis stars, the postal service chose to recognize and honor Mom.”

She and her younger sister, Brenda Brinker Bottum, are still overwhelmed by that. “It’s so exciting for our family, Texas and tennis,” Brinker Simmons says.

The Little Mo was to be one four Forever stamps (those that keep their first-class postage value) honoring women pioneers in sport. Connolly Brinker was the “confirmed choice” for tennis with yet-to-be-determined honorees in swimming, downhill skiing and track and field.

1 / 2The U.S. Postal Service will soon issue a Forever stamp honoring the late Dallas tennis phenomenon, Maureen "Little Mo" Connolly Brinker.(USPS) 2 / 2Maureen "Little Mo" Connolly Brinker in her playing days.(Maureen Connolly Brinker Tennis Foundation)

The service expected to release the four-plate in 2016. But that year came and went, as did 2017.

“Obviously a government entity would want to have their t’s crossed and i’s dotted to ensure that everything is legitimate and properly executed,” Brinker Simmons says. “I probably put in hundreds of hours of conference calls in the last four years.”

First off, Brinker Simmons had to prove that she was the legal heir to her mother’s estate and had the authority to turn over intellectual property rights. “There were a lot of stops and starts and many, many times when I wasn’t sure if this would happen,” Brinker Simmons says. “They would always say, ‘It’s still in development.’ I kept thinking, ‘They have to be at least pushing a little forward or else I wouldn’t continue to get these calls and these approvals.’”

In May, she got word that the Little Mo would be released in 2019 as a stand-alone stamp.

“That was very moving. I wept over that,” she says.

The first-day-of-issue dedication of the stamp will be held at Southern Methodist University, Connolly Brinker’s alma mater and the 1970s and 1980s home of the now-defunct Virginia Slims of Dallas Tennis Championships.

She doesn’t know what happened to the other three sports. “All I know is what I had to do, and it was an arduous task,” she says. “I can’t imagine having to do four.”

Brinker Simmons played a role in every step of the process.

“It’s been unparalleled, let me tell you,” says Mauresa Pittman, senior stamp development specialist for the USPS in Washington, D.C. “She was on it. She cared about the legacy and wanted to make sure we had everything perfect.”

The stamp features an oil-on-linen painting of the tennis star by Gregory Manchess that’s based on a black-and-white 1952 photograph of Maureen hitting her signature low volley.

Toasting Americana

The Little Mo is the latest of the postal service’s Forever stamps that “celebrate the people, events and cultural milestones that are unique to the history of our great nation,” says USPS spokesman Roy Betts. “The postal service remains committed to educating and informing America — and the world — about the many achievements and contributions of noted Americans like ‘Little Mo.’ ”

Betts says that announcing new stamps is his favorite part of his job and that learning the Little Mo story was a wonderful discovery.

“I was like, ‘Wow, I didn’t know about her,’ ” he says. “I’m not necessarily a student of the sport, but I’ve played tennis off and on in the past. Her story is quite amazing. She died young.

"Stamps help bring awareness and educate the masses on some part of American history.”

In addition to the tennis star, the 2019 Forever stamp lineup includes the late artist Ellsworth Kelly, the Transcontinental Railroad and military working dogs.

Connolly Brinker is the third tennis champion to be featured on a U.S. postage stamp. In 2003, Arthur Ashe’s profile and tennis racket graced a 37-cent stamp. The late Althea Gibson, the first black person to win Wimbledon and the top-ranked player in the world in the late 1950s, was honored with a Forever stamp in 2013 as the 36th stamp in the Black Heritage series.

Family standard bearer

“Brenda and I always say, ‘Mom was a remarkable woman who just happened to be a very good tennis player.’ This is the way we saw her,” says Brinker Simmons.

In 1955, the 20-year-old retired tennis star married a 24-year-old Brinker, who was working for the fledgling Jack in the Box hamburger chain in San Diego. Cindy was born in 1957, her sister Brenda two years later.

The family moved to Dallas in 1962, when Brinker expanded the chain to the east.

The girls were 12 and 10 when their mom died.

Norman sat down with the girls and asked what they should put on their mom’s headstone — a pretty hefty question for grieving girls.

They decided on crossed tennis rackets on both sides of the marker with Maureen’s birth and death years and the inscription “A Gallant Lady Wife Mother Champion.”

Maureen "Little Mo" Connolly giving her daughter Cindy a lesson. (Courtesy)

“She was a wife and mother first. That was her dream, to be a wife and mother. And then a distant third to that, she was a champion,” says Brinker Simmons. “Mom was the third-most-publicized woman in the world in the early 1950s in terms of column inches. She was very well-known and popularized and written about. But she was most excited to be Mrs. Norman Brinker.”