Most people who care about such thinks (collectors, stackers, numismatists) know to check the dates of any dimes, quarters, or half dollars that they come across. Anything 1964 and before is 90% silver. Though not super common these days, they still do show up with some regularity. People in the /coins subreddit are always posting about finding them in rolls or at Coinstar machines. I'm not even in the US, but my oldest son has found two pre-64 dimes.