(WARRENSBURG, Mo.) – Bill Burgess places 20-30 challenge coins on a table in the Military and Veterans Success Center, earned over the course of his 20-year career in the U.S. Air Force.

A few minutes later, Dusty Storms, also a veteran of the United States Air Force, noticed Burgess’ coins on the table, pulled up a chair, and pulled out two coins he kept with him in his wallet.

Shortly after that, Denver Todd, another Air Force veteran, stopped by our table and pulled a coin out of his wallet.

The coins themselves were interesting – all varied in size, weight and design. But it was the immediate recognition of and the interactions that came out of those coins that made them truly incredible. Each one had its own significance to the man who had it, and there is a story attached to each one.

There is some debate about the exact origin of the tradition behind the military challenge coins. According to this post from Katie Lange on behalf of the Department of Defense, two possibilities are World War I and the Vietnam War.

Northwest Territorial Mint says the tradition, as it is recognized today, can be traced to World War II, though earlier versions of this tradition are believed to date back to the Civil War.

That tradition has gained more veneration now, attracting collectors from both military and civilian backgrounds. In 2006, Jesse Medford, an Iraq War veteran, established the Challenge Coin Association upon his return home from combat.

There are variations on how the challenge works, but, generally speaking, a challenge is issued when one person displays their coin. If the person being challenged does not have a coin to display, there is a penalty; often times they must buy the challenger a drink.

There is something of a hierarchy involved as well. If a person is challenged and displays a coin they’ve earned from someone of a higher rank or is otherwise of a certain esteem, the challenger is now on the hook for a drink.

There doesn’t have to be a penalty; simply winning a challenge is sometimes its own reward.

Burgess, an airplane mechanic, was coined by Vice President Dick Cheney after his unit repaired Air Force 2 so quickly Cheney didn’t realize the plane was being delayed.

It would be difficult for someone to produce a coin from a higher-ranking individual than the vice president of the United States, and that was something Jeff Huffman, a veteran of the United States Air Force and the director of the Office of Military and Veteran Services, was sure to point out to both of us when he told me, and reminded Burgess, that he’d been coined by President Barack Obama.

One of the coins Storms had with him came from Lt. Col. Kevin Henry.

Henry carried that coin with him on every mission he flew. At the time Storms reenlisted, Henry was retiring. As a token of the respect they had for each other, grown over the time their careers overlapped, Henry presented Storms with that coin.

In Huffman’s office is the best visual representation of what these coins represent to the people who have earned them.

An entire shelf on a bookcase is devoted to the coins he has accumulated, and each one is displayed so it is visible and accessible.

On a table in the corner of his office, in a box under a pile of files and papers, is his diploma.

“I’ve got the space for it,” he said, looking at the wall above his computer. “I guess one of these days I’ll hang it up.”