HAWAII - People go to Hawaii for the beaches and the culture. So, the relics here will be either sand, or flowers from a lei.
IDAHO - Potatoes, again, being food, probably don't belong in cardboard. Idaho is one of only two places in the world where star garnets can be found, so each card will contain a piece of this rare gem.
ILLINOIS - The Land of Lincoln - the only president born in that state. Each card has a Lincoln penny embedded inside.
INDIANA - Home of the Indianapolis 500, so either a piece of the track, or a piece of racing tire will be embedded.
IOWA - Iowa is driven by agriculture, so it's time to put some food in a trading card. And this state produces what could actually work in a card - popcorn.
KANSAS - Kansas is known as the sunflower state. Since the state's basically a giant rectangle, we can easily fit a small sunflower inside.
KENTUCKY - The Kentucky Derby! You saw this one coming. Horse hair has already made an appearance in cards, so either continue that trend, or you could put dirt from the track in the cards, or even a piece of horseshoe from a winning horse.
LOUISIANA - New Orleans and Mardi Gras define this state, so some beads from a necklace will be inserted in every card.
MAINE - Among other things, Maine is famous for its seafood. Each card will include a lobster claw.
MARYLAND - home of John Hopkins University and other life sciences endeavors, each card will include a flattened syringe (without the needle, of course).
More states tomorrow...