Here’s what you need to know:Mickey Mantle’s 1952 Topps rookie card is one of the most sought-after cards. While a Mantle with a rating of SGC 7 like this one is valuable, a version of the same card rated PSA Mint 9 recently sold for $5.2 million.Credit...Jeenah Moon for The New York TimesTopps, known for its trading cards and...