S.Severus denarius, Herennia Etruscilla viminacium, 1 kreuzer Joseph I, fibula, roman brick with stamp on it..etc etc
We had a Roman brick like that, in fact it was a roof tile, found in the river bed, that was marked with the number of the Tenth Legion. Could be something like that.
Awesome finds! I guess I need to just dump my $300 detector. Never have anywhere near that king of success.