Is this rock or petrified wood?

[whippoorwill]

This looks like petrified wood to me but I've had no success looking online to see how to determine if my hunch is real or not. I'd appreciate any help or suggestions about whether or not this is petrified wood. (Item is wet in the pictures)

 

Thanks!

[whippoorwill]

And here is one more piece I'd love help with.

 

Thanks again!

[Andriy]

I think rock

[Righteous]

Can you see any of the rings from the tree itself? 
I have 6 different pieces of petrified wood and can see tree rings on every piece? 
where was it found ?

[Andriy]

Very similar to flint

[whippoorwill]

It was found in a river in Florida. The only area that looks close to rings is the little knob shown in the second picture of the first rock.

[Rockwood]

Sorry. This looks very not wooden to me.

[whippoorwill]

Thanks for the help!