Inspiration: old envelopes

More vintage envelopes and cards found my way! Check out all these stamps!
Some envelopes are a bit damaged, but some are in really good shape! They are all empty by the way, so no secret note inside them, but I could write a secret note in them ofcourse for my penpals. Who knows!
Also some first day postage stamp issues from the sixties, seventies and eighties. The ones from the sixties have letterpress envelopes! Love to glide over them with my finger and actually feel the print (or is that a bit silly?)
I really love the postcard someone has sent to the Queen, right after the second world war, and it returned to sender with a small handwritten message: "thank you for your help to the refugees". But I'm not sure who has written that, I don't think the Queen has written that herself.
What really strikes me about these envelopes and cards, they are from all over the Netherlands. How come they all landed in the same box at someone's house? That's the kind of thing that really puzzles me.