Picking up nuts to sell is a very common thing to do here, one year we paid for Christmas with pecans. But even though this tiny town has like 5 places that buy nuts, nobody buys black walnuts. Last weekend we took a giant plastic tub of them to the lake and hit them into the water with baseball bats. Walnuts in food are almost always English walnuts, a much easier nut to crack.
That looks like a lovely spot for a redbud tree, a smaller native tree with beautiful pinkish purple flowers in the spring right before the pretty heart-shaped leaves come out. They are known to be juglone tolerant. Baby redbud trees do grow fast, but are not weak-wooded trees like pears.
When you have a really fast-growing tree, its' wood is weak, and not able to stand up to strong winds, snow & ice like trees with stronger wood. I would never plant any tree with the primary attribute of 'fast-growing' - especially in such tight quarters where dropped limbs are sure to damage something, and in Cleveland, where you're sure to get ice and snow every winter.
A dogwood might be another option, though it might be a bit too sunny in that spot for one to be really happy. IDK about their tolerance to juglone.
