I don't have Parkinson's but happened to notice your post. We have to be cautious about any recommended supplement because supplements aren't well regulated, at least here in the US. And there are people who are taking many different supplements--far too many, in the opinion of quite a few medical practitioners.

So just to be on the safe side, there is this about Mucuna pruriens (AKA cowhage):

Cowhage: Uses, Side Effects, Interactions, Dosage, and Warning

And this:

Science of Mucuna Pruriens for Treating Parkinson’s | APDA

Good advice here, I think:

Parkinson's Foundation