Have you ever wondered what happens to all those political buttons that seem to be everywhere, from backpack straps to denim jackets, after an election?

Many wind up in recycling bins and under couch cushions, but there's a small group of people out there who collect those buttons, which become more valuable over time. Saturday, a group of local collectors gathered in Titusville, N.J., to buy and swap buttons  at Titusville United Methodist Church. This gathering has been happening since 2003.

"We're curators of history," said Tony Lee, president of the Big Apple chapter of the American Political Items Collectors association. "A lot of this stuff doesn't make it because they're not meant to last. However, people who collect this stuff care for it and make sure it will be preserved."

At the convention, collectors perused everything from shiny "Nasty Woman" buttons from the 2016 election to badges featuring Martin Van Buren's portrait that date from his campaign. One collector had an extensive array of hand-painted pins that featured pro President Trump images. In one, he body-slams a CNN avatar in a wrestling ring. In another, he's seen spanking North Korean leader Kim Jong-un. There were a lot of Franklin D. Roosevelt and John F. Kennedy items for sale, along with anti-Vietnam War buttons.

"Right now, items related to women's suffrage are very popular," Lee said. "People are thinking about the effectiveness of protests right now, so the popularity of items related to that, like stuff from the civil rights movement, have gone up."

Plenty of non-button items were on display, as well, including a handwritten letter by George Washington's nephew  priced at $175, and an invitation to Roosevelt's  inauguration as governor of New York in 1929.

According to Ted Hake, who wrote the Encyclopedia of Political Buttons: United States 1896-1972, the first political buttons were sewn onto clothes. It wasn't until 1896 that the pinback button was invented. Today, button prices are determined by popularity, scarcity, and condition.

"I met my first button in 1948, when I was 5 years old," Hake said. "A woman in an antiques store showed me a box of Liberty Loan buttons and I took it home and stuffed it in a drawer. It wasn't until late high school that I began to collect more buttons."

Hake said he was a coin collector until he made that jump to button collecting.

"I like that there was no one keeping track of these political buttons, even though they're serious works of art, especially during the turn of the 20th century," Hake said. "During college, I'd visit collectors and buy items from them. Then I'd take the buttons to New York and sell them to other collectors at a higher price."

Lee also began collecting political buttons due to chance. His older brother moved to D.C. to attend college and often brought him back campaign buttons, including ones from Robert Kennedy's ill-fated 1968 presidential run. Lee now has buttons from every presidential candidate since 1896.

But not everyone at the convention collects the same things. Lee said some enjoy collecting posters. Some prefer pop culture items. And some choose their collectibles based on tone.

"A lot of negative items were created in this last presidential election, especially about Hillary," Lee said. "So those reached new heights."

A handful of high school students were among the  attendees on Saturday. Although most were there for extra credit for AP history classes at Hopewell Central Valley High School, almost all of them found items there that interested them. Senior Sam DeForte spent 10 minutes  enthusiastically digging through the dollar button bin.

"I really love history and politics," she said, clutching a framed pamphlet from Robert Kennedy's campaign. "This is my first time here and I want to buy everything."

And even if there are political differences between the collectors, Lee said, they don't often come up at conventions.

"Everyone collects different aspects of history," he said. "Everyone is very respectful. What we do is more about recognizing the important things in the history of America. We consider ourselves historians first and foremost."