Transcript for Olympic Sport of Pin Trading
That's another great day for team -- sale here in the UK. Both on the track and on stand behind parliament where. Misty may trainer Kerry -- Jennings retire with their third straight beach volleyball gold. Meanwhile in that big stadium sprinter Allyson Felix a hurdler Aries Merritt. Long jumper Britney resell put on world beating performances. And they benchmark moment for woman's rights in the Muslim world as Sara Carr became the first. Woman ever to compete for Saudi -- track and field just forty -- second slower than the winner but the crowd cheered every step. Despite America's gold rush team USA still in second spot behind China on the medal board after day twelve but if they gave medals. For the manic and enduring. Subculture. Of Olympic pin trading all America would. Wouldn't walk away with a thanks to one man our special Olympic correspondent Julie found he found don't. And got a bit of schooling. They can -- -- right. No other American has brought home more metal from more Olympics then Don big movie that's a -- -- fourteen Olympics. The undisputed king of the one Olympic -- anyone can qualify for in trading. Coming into -- Over -- Don's been pulled ever since the 1980 winter games in lake classic for three decades he's presided over a deal -- in collectors club. Every two years those addicted flocked to this summer and winter games five of thousands. To big tents like -- Hours and possibly how to end up. My wife doesn't armory -- -- nobody comes by -- we'll. -- could someone have been doing -- But we decided to give -- his toughest challenge yet student turned to former olympians and -- intends. Kate -- -- -- -- Summers sanders' fourth time Olympic medalist in swimming. We're -- a competition on the UN attention who has the best collection of you hit the -- head cam very. One goal in their girls. And -- -- contest against -- on the -- there. I'm trying to -- my friend Evan -- and get the best sense possible. Summers -- out of the gates and manages to land some great strains. Like that -- insignia. -- -- -- -- -- This is my first official trade I want you to know what's your name. Coming on -- -- -- -- -- -- But I fear I'm beginning to stumble and now. Rejection and it can't walk away there reject it and did I find out why and I hate to tell -- -- -- The group. Then I pull out -- secret weapon. All right now the good stuff comes out handgun -- it. -- here. -- hold on rare boots on the Olympic Committee ten subtly on the back in the game. But summer's not far behind. Larry Craig I think well -- we ended dust settles. Don comes in to make his final decision. -- you've got in the dreamland. Susan but even -- summer is loaded up with more -- -- -- something that pushed me over the top. NBC news are not allowed -- BC's Nightline. I have -- through truly want. And suddenly I still thrill -- victory pulsing through my main answer or maybe I just poke myself but one of those cents. Whatever it is I am an Olympic ten champion. Former reform -- In London I'm Julie Saudi for Nightline.
This transcript has been automatically generated and may not be 100% accurate.