The first pic is brass with a shield shape face.I thought maybe a seal of some kind,but it has no markings.The second item seems to be somewhat heavy brass and has rings going around the underneath. The stem looks like it was broke.I have no idea what it might have went to.
2nd item is not an engine valve. Those have beveled edges where it meets the seat. Also the stem blends into the head gradually, not at a 90 degree angle. I'm more inclined to agree with Breezie on that one.