I got pawpaw seeds because of their anti cancer propertys.
But if you worry about neurotoxins, i recomend any Hericium species or Lignosus rhinocerus. They promote nervecell growth (i recomend a hour before you learn something new, that way you learn it faster and beter).
My ducks found somewhere neurotoxins. Lost many last year because of that. They always died a slow agonicing death, where they get slowly paralized. Until i gave them hericium. They where cured in a single day.
Still haven't found the source of the neurotoxin (free range) - but i just give them hericium preemtively.