Saoutchik, the card thing is annoying. I just had a credit card from Amazon cancelled for the same thing. Those people were in Brazil. Were the Croatians buying fun things with your card? I know ArtFriend is buying bacon with mine
I have no opinion on flowers this year. I haven't done pots this year yet. If you have an actual mailbox on a post you could try clematis or morning glory. I've got morning glory all over my back yard. It came from outer space since I didn't plant it. It just arrived. Like The coriander/cilantro plant, the squash or gourd that popped up. It's an interesting mix of junk