Your third item is a coin.
Totallly Awesome ID on this.View attachment 1999325
Here it is:
Worn by US Navy officers. Many of these beautiful, early US Navy buttons were British made. NA-66C per Record Of American Uniform And Historical Buttons, by Alphaeus H. Albert. Backmark: " NE Plus Ultra / Treble Gilt / Stand Colr" Button is flat with 16 stars. Size: 23 mm (almost 1").
About your third item:
According to the 1907 J.M. Eilers & Co. saddlery & horse-equipment catalog, your find is a Johnson's Pattern gag-runner -- which is a component of a horse's bridle. See the image of the relevant page from the 1907 Eilers catalog attached below.