I was thinking the same thing, but I've also seen some elm do that.... Black gum (aka tupelo) can make a woodsman hate the chore in a hurry!
We did a really big one up at scout camp years ago, it was completely hollow almost the entire way up the trunk and FULL of brown crickets (I mean FULL of them, HUNDREDS)! Gave that tree to another dad that helped me up there all the time, he tried splitting some of it and ended up putting those pieces in his OWB WHOLE. It wouldn't split for chit.
Gum wasn't very yellow when splitting either but I've never seen mulberry do that, not even a little. The black gum my BIL and I milled had a dark core. So I'm ruling out black gum.
Guessing sweet gum, my least favorite wood! I might even dislike it more than elm simply because I hate the gum balls mess it leaves every year. And how difficult it is to split!
Another vote for gum, sweet gum. The bark does not look like any elm around here; it looks much more like gum bark.
I agree with Brad ,I don't think it looks stringy enough to be elm .The more I look at that bark the more puzzled I am.
It is stringy looking that's all I know for sure. Agree with huskihl on color. The Cottonwood I've seen is much greyer. It is wood and it is already split, therefore it should be good to burn!
I put a like on this post early on, and I'm sticking to it. Black gum. Tupelo. Nyssa sylvatica. All the same tree, called something different, depending on the part of the country you are from.