Top and bottom rows are the 1902 Great Seal button design, that is still in use today. The button with the 2 on it, is a 2nd Infantry button possibly from WW1. Those are some nice button finds.
They would make a great little display to hang on a wall.
I agree with Trezurehunter that the collar disc is WW1 and it is from the 2nd Infantry Company I. I have not seen the small great seal piece you have pictured in the middle of the second row before.