Need help figuring out this skull

[LMI]

I found this piece of a skull in very shallow water of a nearby river. There are woods around it also. It is odd to me because I have done several searches online and so have several friends and none of us can find what this is. If we find something that it resembles, the teeth dont match the animal, or if we find what the teeth should belong to then the skull does not match. It is about 4 inches long. Even though it is small I believe it was older because the teeth look pretty worn. I think it was also a plant eater because the teeth are very dull. But obviously I have no clue. Just give a best guess.
Thank you for anyone who can give me some idea!

[JackBean]

quality of your pictures is not very good. Especially those on right are focused on the things in back, not on the skull

[LMI]

I know the pics arent great. All I have is my crappy cell phone camera. is there a better angle that may help? I can try more pics. Would more of the front view help?

[JackBean]

at least, don't pick it up and don't put it so close to the camera, because it cannot focus then and focuses on the background I had the same problem, when I tried to take a picture of some spiders on their net. And they were quite big

Anyway, back to the problem. It looks, it doesn't have big incisors or canines, so I would guess it's skull of some herbivore or omnivore or something like that But it looks quite small, right?
Nevertheless, as you don't have much from the skull, the only way to determine it is to focus on the teeth.