A few years ago, Bud Kling had three rooms added to his house in the Pacific Palisades in California. The builders used extra concrete along with a reinforcing metal beam — and not because Mr. Kling was expecting a crowd. The rooms weren’t for people. They were designed to house and showcase his 30,000-strong collection of Olympic pins, the colorful and endlessly varied souvenirs that have been bought and traded at the Games for decades.
Even when the builders were finished, Mr. Kling, a 74-year-old tennis coach, still had far more pins than he could fit in his home.