I feel your pain! Ohio State University has a page on that...but I found this link more helpful since it also had photos of some.

http://www.mortonarb.org/tree-plant-advice/article/887/plants-tolerant-of-black-walnut-toxicity.html

We have a honeysuckle shrub real close under the walnut tree which has a juglone roots issue as well. And it is thriving and has been there for about three years maybe. Bloomed beautifully too.

Rose of Sharon do well...a neighbor of mine has a few planted under a walnut tree and it doesn't seem to phase them.

Good luck! Once you find what plants do well...success is a good feeling!

Anything Prunus seems to do well near Black Walnut. Cornus also seems to tolerate Black Walnut roots well. Avoid Pinus or the other needle trees. They all have died here after a few years.

I have many shrubs/trees growing right under or very near a very large black walnut and all are doing well. The list includes Norway Spruce, many cultivars of Hemlock, Viburnum dentatum, Mockorange, Physocarpus 'Summer Wine', Arbor Vitae, Chamaecyparis, Snakebark Maple, Redbud, Cornus alternifolia, Cornus sanguinea, Forsythia, Carpinus caroliniana.