Starbucks's pumpkin spice latte has become a cultural phenomenon, to say the least. Memorial Day is to summer as the PSL drop to fall, you know what I mean? It's hard to even remember the first pumpkin spice latte I ever sipped, or when we started associating the coffee conglomerate's pumpkin spice recipe with the change in the seasons. Let's revisit history, shall we? Find out how much you know about the saga of the PSL.