This must be self-explanatory.
Yachts might have made a nice collage, except that I have only one, or at least only one that I can find. I've discovered over the last few weeks that I need a better filing system. Young could have been another theme: young animals, young children.
I did consider "yesteryear" showing some of my vintage postcards but vintage cards don't really look great as a collage. they are better viewed singly.