The civil war yankee 3-groove Minie-bullets on each end of the row are definitely fired ones. BosnMate is correct, the one on the left shows a circular indentation made my the ramrod's mouth during loading into an ash-clogged rifle barrel. Both tumbled due to passing through thick bushes near the end low-energy end of their flight, picking up some denting to the bullet's thinner-walled base.
The middle bullet is hog-chewed. The "pain bullets / hospital bullets" myth has been solidly debunked, for several reasons:
1- There seems to be no historical records of soldiers being given a bullet to bite on during surgery. The last thing you want to do is put a swallow-able object in a person's mouth when they are in agony. Instead, a strip of leather or twisted rag was used.
2- Human jaw muscles do not have enough "bite strength" to significantly deform a 1/2"-thick slug of solid lead. (Do a Google-search for the terms "bite force" and "bite strength.") However, certain large animals, such as hogs, do have enough bite-strength. They bite on the bullet because they think it is an acorn. They keep chewing because lead tastes sweet. The Romans are infamous for having used lead to sweeten wine... an unknowingly toxic practice which some medical folks theorize contributed to the decline of the Roman Empire.
3- Even if a human's jaw muscles were strong enough, human teeth are not. They will crack if you bite down too hard on solid objects. I personally chipped a jaw tooth from biting a bit of beef-bone in a hamburger.
In a previous discussion about the "pain bullets" myth, I almost posted a bet which involves literally "putting your money where your mouth is." I would bring a typical pure-lead Reproduction .58 caliber Minie-bullet to a relic show, and I'll have $50 in my pocket, to bet anybody who is willing to test his belief that the chewed bullets we dig are actually soldier-chewed "pain bullets." The challenge is to bite the .58 Minie-bullet hard enough to make it look like the chewed ones we dig. If the biter won the bet, he could then put the $50 to toward his $1,200 dental reconstruction bill. But I won't actually offer that bet, because somebody would sue me after he lost, for enticing him to injure himself.
BosnMate is also correct about the circular iron disc with a round hole through its center. It is a spacer from a disc harrow or similar farming equipment. I've dug several in farm-fields.
Sure does look like tooth marks to me. The right hand bullet was fired, 
