Black locust... robinia, darn, somebody.
That punky heart is very common. There is a locust borer, a fungi, a leaf miner, lots of stresses on this fast growing colonizer. Here they come in 3 or maybe 4 grades. Timber, on the rare occasions when one yields a nice 6x6 or 6x8. Next is fencepost, with some defect. Then landscape timber for raised beds in the garden. Firewood comes from what you are showing but if the other side of that tree isn't doty I'd throw it on the mill and at the very least make dimensional firewood on the way to looking for that nice timber. Grubbing them out is a chore.
Mockernut, white hickory has a wide pretty bright white sapwood and then a red brown heart with lots of streaking and usually bird peck.