Whoa, black walnuts taste totally different than regular walnuts. Not sure where to find walnut, and I'm not sure what you could possibly substitute for it. you could maybe try some french toast and add some raisin and apple to it?
I was thinking maybe pecan; they're not all that diffrent, though walnuts are drier. Maybe Rocky mtn vapors has some, they have a bunch of savory flavors.
And yeah I found out that while black walnuts make outstanding ice cream, they just overpower everything else in baked goods. However, one year I used just a *pinch* of black walnut in with the regular chopped walnuts, and THAT was great!!
Andria