John7664, welcome to T-Net and the What-Is-It forum. The guys over at CivilWarTalk know me as Peter C. (Pete) George, for co-authoring the book "Field Artillery Projectiles Of The American Civil War." Thanks for the good photos, and in particular, showing the shape of the ball's fuzehole and telling the hole's measurement. It appears to be a 12-Pounder (4.62") caliber explosive Common-Shell cannonball. ("Common-Shell" meant a "plain" shell, no antipersonnel balls inside it, just gunpowder.) A 12-Pdr. Common-Shell was specified in the Ordnance Manual of 1861 to weigh about 8.3 pounds, which is just slightly off from the weight you reported. I think if you use a Pi Tape (a.k.a. diameter-tape) you will find the ball's actual diameter to be either about 4.50-to-4.52-inches (civil war era) or about 4.45-inches (Revolutionary War era.) The wooden-plug type of fuzehole (no threading for screwing in a metal fuze) dated from the Colonial Era through the civil war... so you'll have to get the ball's exact diameter measurement to tell which time period it is from.
Up until the late-1840s, all cannonballs had the wood-fuzeplug type fuzehole. During the civil war, the yankees had some wooden-fuzed 12-pounder cannon shells until Summer 1862, but then shifted to metal fuzeplugs. The Confederates used the wooden-fuzeplug type all the way through the end of the civil war. So, if your ball is the civil war era size (4.50-4.52"-diameter) it is far more likely to be a Confederate-made one than a yankee one.
You didn't ask, but because many people want to know... a 12-Pounder caliber Common-Shell with wood-fuzeplug type fuzehole, and without a pentagonal/rhombohedral powder-cavity, in the same condition yours is in (having no rust-encrustation, and very little rust-pitting) sells for about $175-$200 at civil war relic shows. Please note that I said "sells for"... you'll see higher pricetags but I'm talking about what they usually wind up bringing after the haggling is done.