And then she ordered more American flag lapel pins.
For more than 30 years, the country's military entanglements have been illustrated through the merchandise Cox stocks in her store: the military ball caps and T-shirts, the American flag presentation boxes, the challenge coins, bumper stickers and lanyards.
War is good for business. And the Ship's Hatch has been good for warriors.
"The majority of our customers are military," Cox said. "We've got a lot who are not, but maybe they're buying for their father. The military is very patriotic. Generally speaking, there's a patriotic bent to the people who walk in here."
Cox got her start with the product that gave the store its name. In 1973, Cox and her husband, Tom, bought 15 rough wooden hatch covers of the sort that covered the holds of U.S. Liberty ships that crossed the oceans during World War II. Sanded, sealed and placed on legs, the hatch covers made unique tables.
When the craze for repurposed hatches waned, a different item exploded: baseball caps emblazoned with the name, hull number and silhouette of Navy ships. Then Cox moved into custom jobs. In 1986, the woman who sold her the hats convinced Cox she should capitalize on the popularity of a Tom Cruise movie and sell a cap that read "Top Gun."
Those flew off the shelves like an F-14 off an aircraft carrier.
During the Iran-contra affair, Cox whipped up hats that read "USS Oliver North."
Said Cox, "Lots of military people got the Oliver North hat."
She sent a few to people at the White House, including the secretary of shredding, Fawn Hall, and Vice President George H.W. Bush.
"I am in full support of naming our next nuclear aircraft carrier after Lt. Col. North," wrote Hall in her thank-you letter.
"Love that cap," wrote Bush in his. "Ollie North sure came out ahead of his loudest critics."
The Ship's Hatch might not work in, say, Adams Morgan, but it's perfect for subterranean Crystal City. The store took a hit after the BRAC base closures, but there are still plenty of uniformed shoppers nearby, including at the Pentagon, two Metro stops away.
Need a pair of "Go Navy. Beat Army." socks? The Ship's Hatch has them — along with ones that read, "Go Army. Beat Navy."
They also sell official U.S. Marshals Service items — but only to U.S. marshals.
Said Cox, "Tourists are always disappointed because they want the [challenge] coin or they want the hat and I just can't sell it to them." (Too much risk of someone wearing the hat and flashing the coin and getting into mischief.)
There's a small selection of MAGAiana, too — small and controversial.
"I just found out some lady gave me a bad review on Yelp because I have the Make America Great Again hat," Cox said. "I think I know who it is. We used to have a full-size Trump cardboard stand-up. She used to come by and say something negative every single day."
Cox is bipartisan: She had full-size Obama cutouts, too. "We sold them all," she said.
Among the most popular items at the Ship's Hatch are things emblazoned with "Trust me! I'm a Colonel." People buy them as promotion gifts.
"There are so many colonels in the Pentagon, it is almost laughable," Cox said.
Cox, 73, is retiring Wednesday, but the Ship's Hatch will sail on. Becky B. Shagdarsuren, who managed an engraving shop around the corner and has been interested in owning her own business, has bought it.
And Cox will be back at the store for Memorial Day weekend, when hundreds of Gold Star families come to town. Every year, Cox said, some of them stop to shop at the Ship's Hatch even before checking in at their hotels.
What are they looking for, I asked.
"Anything with a gold star on it," Cox said. "We have a Gold Star mug that we can put their loved one's name on, or a picture. . . . It's kind of a memorial."
In a city of memorials, sometimes the simplest ones are the most moving.
For previous columns, visit washingtonpost.com/people/john-kelly.