I exceedingly appreciate postcards with photos of astronomic items (e.g. supernovae, planets, galaxies, stars) or wild flower fields (and especially photos of poppies).
Also, I like postcards from Amnesty International, European Capital of Culture, events, exhibitions, Greenpeace, UNESCO World Heritage Site, UNICEF, World Expo, World's Fair and postcards with famous persons (also sportspersons like basketball players or hockey players and ballet dancer) from all over the world, as well as all characters from "The Peanuts" (Charlie Brown, Linus,Lucy,Snoopy,Woodstock...) and I am always very delighted when I get a postcard with The Peanuts from Japan or elsewhere.
But I am also pleased of funny postcards, especially with black humor or irony.
Particularly, I like colorful stained-glass windows of Cathedrals (e.g. Amiens, Chatres, Cologne, Zurich...)
However, if you don't have any of my preferred cards, so you can send me a card with something I should have seen in your country.
If you like, please write me the first line of your favorite poem.