Doesn't black walnut have that weird terminal leaflet usually?

It does look like white walnut - Butternut.

I noticed that terminal leaflet. Black walnut does sometimes have it. That's why I said "probably". But I would go along with butternut. Which might explain why the tree was cut down.

Agreed.

Thanks all. Reading up on butternut, now I'm a bit sad to beat back these suckers. If this was a butternut, that's a shame because they seem to be lesser known and being further decimated by disease. Unfortunately this isn't a great spot for a tree revival experiment and I doubt these suckers will grow into a productive tree form.