While baseball cards may have originally taken the collecting world by storm (Mickey Mantle’s 1952 card once sold for $12.6 million), it is rookie American football cards that have come to dominate the market, valued by both die-hard fans and collectors alike, with entire festivals devoted to them.

Topps and Panini are considered the top brands in the game, producing highly coveted card packs that even athletes themselves have begun to collect. While companies produce cards for each football season, rookie cards are the most valuable.

Rookie cards honor that inaugural year in a guy's career, produced just once to celebrate that special time before anyone knows who he will become. Recognizing someone’s potential and getting a hold of their rookie card before a career is born is the sign of a smart fan and collector.