Ben Zaricor was a college student in St. Louis in 1969 when he saw this guy in a band get beat up.

Students getting pummeled wasn’t an entirely unusual experience on campuses in that tumultuous era of Vietnam and Kent State and Watts and civil rights marches, but what Zaricor couldn’t get over was the reason the guy got trounced — he was wearing a Stars and Stripes vest. Like he was Captain America in “Easy Rider,” with the flag on the gas tank and Peter Fonda’s helmet.

“And he nearly got beaten to death,” says Zaricor, 63, the former chief executive of Good Earth Tea and still managing partner of the Zaricor Flag Collection. “People thought he was desecrating it. It struck me not just that this was a symbol people were willing to die for. They were willing to kill for it, too.”

This impression was the beginning of one of the nation’s premier collections of American (and other) flags, some 3,500 patriotic banners and military symbols from over the centuries. Zaricor has spent 40 years and millions of dollars amassing the collection, much of it from the days before the Civil War, when there were few official standards of precisely how the U.S. flag should look (exact shades of colors, size, arrangement of the stars, etc). He usually keeps the collection in a warehouse at an undisclosed location near his home in the San Francisco area.

Flags — several of his are on display through Thursday at the 45th annual meeting of the North American Vexillogical Association, at the George Washington Masonic Memorial in Alexandria — are the iconic image of how a nation sees itself in a single, wordless image, Zaricor points out. He’ll use dozens of examples of his collection in a talk Thursday at 12:30 p.m., giving the Washington area a rare peek at what experts say is one of the preeminent collections of flags in the United States. (The last time he staged a display in the area was in Baltimore in 2005.)

“He’s worked long and hard at it, and he’s a real professional,” says Whitney Smith, founder of the Flag Research Center in Winchester, Mass., and one of the world’s top flag experts. (Smith has written “something on the order of 50 books,” one with Zaricor; has a library on flags of 17,000 volumes; and designed the flags of Guyana, Aruba and ­Bonaire.) “He’s really brought things together so that we have a sense of some of the older [American] flags.”

Zaricor started out by buying two Canadian flags in 1970. He was always interested in the history of the individual flags, he says. New ones out of the bag never interested him much. They had to have a story, and that story had to be able to be proved true. The first American flag he bought was his 25th overall.

“I never even told anybody outside the family I was collecting flags until about 25 years into it,” he says. “I always picked them up from yard sales or estate sales. There was never a day when I said, ‘Okay, today I’m going out flag hunting.’ ”

His collection includes eight original 13-star flags known to exist from the era of the country’s founding — more, he says, than any other collection or museum. He has an 1805 Union Jack from the Battle of Trafalgar, the last documented flag from that battle. He paid “about half a million” dollars at auction in 2005 for two flags that were flying on President John F. Kennedy’s motorcade when he was assassinated. Zaricor has flags flown by Buffalo Soldier units and some used by various battalions in the Civil War.

“I was traveling in my job, and I’d sort of keep an eye out for things as I went. Flag collecting was a backwater. They were considered utilitarian, they were thrown out. . . . You had to work very hard to establish the provenance.”

By the 1990s, auction houses were starting to recognize flags as a collectible item, and he started attending those, buying up entire collections, keeping them intact but placing them within his own, larger collection.

Vexillology is the study of flags (but you knew that), and about 100 delegates from 25 countries have turned out for the four-day conference, says Hugh Brady, president of NAVA. The organization, which has 345 members, is part of the worldwide International Federation of Vexillogical Associations. This is the first worldwide gathering on U.S. soil in 25 years.

While the group studies the arcane and technical matter of flag-making (thread counts, weaving styles, fabrics), and the academia involved in verifying historical flags, they are also out to see the rare and the unusual.

“A lot of people came to this particular conference just to see Mr. Zaricor’s flags,” he says. “It’s one of the top three [collections] in the United States.”

Brady and Zaricor are both eloquent on the subject of flags, how they’re emblems of the government, flown at every federal and state institution, but also deeply emotional icons of the people. When American athletes win an international competition, they reach for the flag, drape themselves in it, weep while holding it aloft.

What does that red, white and blue symbolize? Home? Us vs. them? Personal and public pride? Some of everything, no doubt, which makes the often ordinary items (cloth, stitching, materials worth a few bucks) timeless. Though Congress often wants to make destruction of flags a crime, Zaricor disagrees.

“I don’t think we have to protect the flag from its people. We have a bottom-up, people’s flag. It wasn’t created by the government and handed down. . . . People are amazed when they see all the designs. There are hundreds.”

He wasn’t born with the kind of money the collection has required. He graduated from Overton High School in Memphis in 1965, then started taking night classes at Washington University in St. Louis later that year. It took seven years for him to graduate with a degree in sociology.

After he moved out west and started his tea and herb business, he traveled to China and other parts of Asia, developing teas for his company back home. He built it into a national brand and sold it in 2005.

Today, the flag collection is a family enterprise, with his wife, Louise Veninga, a historian and author, as co-collector and their daughter, Karen, working as a partner in the company, assisting with the research. Though the family still franchises Good Earth restaurants and other businesses, he says the collection has blossomed into a family mission. The company is not a nonprofit, but he funds it privately and says he’s “never sold a flag.”

“Every time I spend $20,000, $30,000, $40,000 — it hurts,” he says. “This doesn’t come cheap. But there’s so much history here. It’s about the country, and who we are.”