I sure do remember the submarines - marvel of science, the way they'd sink and float.

Yes, Sourdough, I remember the little grey airplanes. I managed to collect the whole set and had them for years.

Another set of things included miniature license plates from each state (48 states then of course).

I also remember little metal critters, such as a frog and a bug of some sort. They were made of tin and when you pressed down on the back, they'd then pop back up with a clack and the varmit would jump. Don't remember what kind of cereal they came in, though.