I was married in Mexico a few weeks ago, and thought we had collected a large number of cards after the wedding. However, when we got home, we only had a couple. Everything was thrown into a bag and the bag into the suitcase. We didn't open the bag again until a week later we got home from our trip, so we hadn't realized things were missing until we were contacted about uncashed checks given to us in cards at the wedding. They could have been taken anywhere, the resort, the airport, customs, who knows, but it's too late to do anything about it now. Definitely open your cards, write down who gave you what, and keep them all in a safe place the day after the wedding.
"There is always some madness in love. But there is also always some reason in madness."
-Friedrich Nietzsche, "On Reading and Writing"