Found this in the dirt with some older items that appear to be from the late 1800's - early 1900's, little glass medicine type bottles and a piece of purple glass the looks like it could be a part of a bowl or something.
If you haven't already get a gps tag so you have lat/long coordinates and take it to your local museum. Chances are they'll have a fairly detailed list of what went on there artillery wise and between location, size and shape they should be able to narrow it down.