There's (minimal) research on psilocybin doing just that. One of the tragedies of prohibition is that we just weren't able to study these psychedelic compounds easily for 50+ years.

Not to take away from your point about psilocybin but the mushroom brought up, lions mane, is not hallucinogenic.

For sure, and lions mane is one of the three things Paul Stamets has been talking about for years to take in combination with niacin and psilocybin (microdose) to support neurogenesis. Low doses of psilocybin have only very mild perceptual changes, much less than smoking weed or drinking alcohol (for me).

Have any sources? I’d love to read what you are thinking about.

I haven’t used psilocybin in a clinical setting but have gone through an alternative psychedelic-assisted therapy process. Very interesting results and many positives.

There's not a lot, unfortunately. This paper is a literature review and the claims are weak, but there's something there that should be investigated further: https://pmc.ncbi.nlm.nih.gov/articles/PMC12392120/

Paul Stamets has evangelized psilocybin + lions mane + niacin for years in a microdosing format, but again, the research is lacking largely due to prohibition.

Not necessarily neurogenesis, but evidence of neuroplasticity: https://news.ycombinator.com/item?id=48030098