Paul stamets took an atrocious amount of psylocibin mushrooms in the middle of the woods which supposedly cured his stutter. The dude is a huge advocate for mushrooms in general though. Idk about lions mane, heard good things. Side note, i believe some people stutter because its a trauma response that manifests in speech. Psychadelics are able to heal trauma and can potentially help with stuttering with the wholw rewiring of the brain stuff.