Other strange pieces

[JDelva]

Hello,

So I went back on the field near Ypres with my metal detector and found some nice stuff. During my excavation, I found 2 pieces that I don't know what they are.

The first piece is like a copper nut with holes on the side, I am not sure if this piece comes from WW1. It has a diameter of 2cm and is 1,5cm high.

The second piece looks kinda familiar to me, but im still not sure what it is. This piece has a circular diameter of 5cm with a hole of 1,2cm. It looks like the hole is smashed out by an explosion.

Would anyone happends to know what those pieces are? 

Kind regards

Jobbe