No
experience with Black Walnuts, though we do have closely related Butternuts. What seems to do well with them, that I'm aware of, are native wild grapes (I guess that
should be Muscadines for you) & what we actually have are Hawthorn/ Crabapple & the Black Raspberries previously mentioned. We also have a ridiculous patch of Woodbine there worse than just about anywhere else I've seen & I managed to get one of my Eastern Sweetshrubs started alongside that spot too. Also had a
Morel Mushroom growing there about a month ago, but just the one. Sadly, that spot is also badly clogged up with things like Buckthorn & Privets.
Across from that patch, I managed to start a three trees & a bush after clearing out some invasive grapes & buckthorn, though I still don't exactly know what all is even there other than a plum. Other than buckthorn, what was already in that spot were Milkweed, Dogwood & a Mulberry.
Some things I attempted to put there that didn't even attempt to sprout-- Wintergreen, Eastern Red Columbine & Cranberry, but I don't know if that is my fault or not. Fire Pinks also didn't grow, but I know for a fact that one was my fault.