What does this look like? It's on my sons chest.

You can always bring him in and have a doctor look at it. If it's eczema they'll tell you what to put on it. If it does happen to be ring worm, its still not a big deal, but you'll have to put an antifungal on it.

Should I just keep an eye on it?

It doesn't feel dry! Ringworm is the first thing I thought

Yup. Freaked me out first time too. If it's dry it's probably eczema. Ivy gets them in circles like this too. First time I saw it, I thought it was ringworm.

It freaked me out cause it's in a circle

Looks like eczema.

Looks like a dry patch. It could be eczema but honestly just looks dry and irritated.