Possible, seems a little small to be case shot, canister shot or grape shot to me but I'm no expert.
Google those terms and plenty of info will pop up from many forums.
http://www.treasurenet.com/forums/civil-war/145780-canister-case-shot-whats-difference.html
Some measurements for civil war armaments, here.
http://www.civilwarartillery.com/shottables.htm
Hope it's something cool, it can be thrilling if it turns out to be great.
I found something a little larger 10 years ago in a public park and had no clue it was military, almost threw it away until I posted a pic here and I was quickly informed it was not junk but probably a canister ball...a great find.
Still one of my most cherished treasures to this day.