Why collection?

What's the connection between postcrossing and wedding? I'm explaining in the short story..

The begining of our relatives (with postcrossing in the background): 
My fiance and I met on the competition (we were one group also with my friend). We spent great time together but didn't exchange any contacts.. But he decided to find me :) At first he found my friend in facebook and talked her into giving him my address. Why? He knew that I love postcards (in the day we met, I'd bought postcards for postcrossing and showed to him). He maked that I got lots of postcards from all over Poland (and other countries) with birthday wishes. One of it was from him (anonymous) with date and place our first date.. The cards are still very important in our relatives.

So.. 
I really want to make my fiance suprise. I'd like to give him wedding wishes from all over the world! We're going to have the wedding in the summer of 2014, but I'd like to collect as much as possible cards.