Since black walnut trees affect the plants growing around them, do the yields of more tolerant plants have yields affected by the toxin to produce less?
Does juglone (an allelotoxin from black walnut) affect (positively or negatively) the yield of juglone tolerant crops?
Look into allelopathy... it's talked about in this SE as well as around the internet. I'm certain that this is a long winded answer with lots of examples. In general, allelotoxins affect the field like the desert provides a life for cacti. Without the desert, cacti would be out-competed by other plants. Although I would expect that very few plants would be positively affected by juglone, I'd bet that there are a few... besides other walnut trees... perhaps parasitic plants like trumpet vine would be stimulated in the presence of juglone (I asked myself this question years ago as I was considering how well the trumpet vines were growing on the walnut trees in my area).
Allelotoxins, like juglone from black walnut and sorgolene from sorghum, have been studied for many years to improve crop yields with rotation and companion planting- and for making herbicides- and for other discoveries. There are some new herbicide products on the market derived from the research.
Juglone especially affects tomatoes and solanaceous plants.
Here is a good read about Juglone: A SUMMARY OF EXTRACTION, SYNTHESIS, PROPERTIES, AND POTENTIAL USES OF JUGLONE: A LITERATURE REVIEW