Welcome to the Civil War Projectiles forum, Lindsay.
I'm one of the ol'timers who hangs out here. Although digging and dealing cw artillery projectiles are my specialty area of relic study, I was a cw bullet digger and (small time) bullet dealer for about 40 years.
As you'll see if you spend some time reading back through the previous posts in the Bullets forum, super-precise measuring of a bullet's diameter, and weight, are generally necessary for determining the bullet's correct identification. That requires precision measuring tools such as a digital caliper, and a Jeweler's Scale.
Precise measuring is particularly neeeded for roundball identification... because there are so danged many kinds of round (and round-ish) lead balls. For example, the larger lead ball you posted could be a musketball, or an artillery canister-ammo or case-shot ball. The latter tends not to be perfectly round... aka a "true sphere."
According to the book written by fellow forum members Jim and Dean Thomas, "A Handbook Of Civil War Bullets & Cartridges" -- a .69-caliber musketball is within a few hundredths-inch of .648" in diameter and weighed about 408 grains. A .54-caliber musketball is within a few hunderedths-inch of .536 in diameter and about 221 grains.
You'll notice that muzzle-loader bullets are a little bit smaller in diameter than the gun's caliber. However, breechloader bullets tended to be a bit larger than the gun's caliber. For example, a .52 Sharps Breechloader Rifle bullet ranged from .538 to .560-inch. Also, revolving-pistol bulets (including balls) are within a few hundredths-inch of .464" and weighed about 138 grains.
Based on comparing your lead balls with the quarter in the photo, I agree with Divedigger, suspecting the larger one is a .69 musketball, and the smaller is a .32 buckshot. It can be very difficult to accurately distinguish a civil war buckshot from "later" ones. What most of us tend to go by is the amount of patina (white or white-ish lead oxide) on the buckshot. Civil war buckshot was made of pure lead, and "later" buckshot was/is made of hardened lead. Pure lead tends to develop thick white or white-ish patina from a century out in the weather, and hardened lead tends to have a thin dull grey-ish patina.
Your third object seems to have a lot of rust on it. There were very-very few iron/steel bullet, and none in the civil war. The object might be a steel-jacketed 20th-Century bullet, or a steel arrow-point. I am not an expert about such things, so I might be wrong about your third object's ID.
Again, welcome to the forum. We hope to hear more from you. A major part of this forum's purpose is to provide helpful educational information to diggers and collectors... especially those who are new to the hobby.
Regards,
Pete