The larger two of your solid (not hollow) metal balls are out-of-round, therefore they are definitely not cannon balls. The reason: ALL actual cannon balls absolutely HAD to be very carefully manufactured to be perfectly round -- lest their out-of-roundness cause them to jam in the cannon's barrel during firing, which could cause the cannon itself to burst violently, killing the artillerymen. Therefore, a big part of an Ordnance Inspector's job to was to make sure that EVERY cannon ball supplied to the artillerymen was perfectly-round.
Your two smaller solid metal balls are perfectly-round. So, there is at least a possibility that those two are artillery "antipersonnel" balls (which were called Canister-balls). To find out for certain, you will need to do SUPER-PRECISE measuring of them, using Digital Calipers. Then check their precisely-measured diameter to see if it matches up with any ball in the charts here:
www.civilwarartillery.com/shottables.htm
For detailed instructions, plus a lot more information on how to determine if a metal ball is really-&-truly a cannon ball, go here:
http://www.pochefamily.org/books/SolidShotEssentialsMod.html
As I said in a previous post at TreasureNet:
The problem about correctly identifying a metal ball is that there are literally millions-&-millions of civilian-manufactured (not military) metal balls which were NOT manufactured to be a bullet or a cannon projectile. Some examples of the "non-firearms" types of metal balls are:
ball bearings
ore/rock/gravel-crusher balls (from the Mining & Stonemilling industry, thus they're also called "mill balls")
"ornamental" balls (such as a gatepost-top)
Sports Shot Put balls
"tumbler" balls (used for polishing or cleaning - for example, iron balls are used to clean dried cement out of the inside of a cement-delivery truck's tank)
Often, the balls listed above will look a lot like a cannon ball, a Grapeshot-ball, or a Canister-ball ...but in actuality they are almost always one of the Civilian-use types of balls. (More than half of the Solid-Shot (solid metal, not hollow, no fuze) "cannon balls" shown for sale on Ebay are a Civilian type of ball, mis-identified as being a cannon ball.
IMPORTANT NOTE: If a solid (not hollow) metal ball is out-of-round (not a perfectly-round sphere), is it absolutely not a cannon ball!