If the trauma surfaces and you have a negative reaction, it's likely the trauma could still be affecting your behavior and thus your life in some way.

It's your decision if the pros outweigh the cons in your situation, but in my experience tackling trauma head-on in a safe environment has measurably improved my overall health.

As someone who had a similar mindset about my childhood, I'd like to share that you might be wrong in thinking they're "resolved" if "dredging them up" still stirs negative emotions in you. Also, even if it doesn't directly, there are other parts of your daily life that it might insidiously influence without you even noticing. So, if you have never talked to someone about these things (I'd suggest a professional, friends and family can inadvertently cause trauma reactivation by offering help or advice, and that can be very dangerous depending on the trauma, especially if gaslighting was involved).

But regarding mushrooms: on their own, I believe they're not that useful for healing. I have a (layman's) theory that post-trip therapy is probably more successful due to increased neuroplasticity of the brain[1]. There was also some research that suggested the DMN gets a bit "scrambled"[2], so another of my layman's theories is that it's able to reach a new "equilibrium" once it was kicked into this unstable state.

[1]: https://www.biorxiv.org/content/10.1101/2021.02.17.431629v1...., and a more easily digested version is here https://www.sciencealert.com/one-dose-of-psilocybin-regrows-...

[2]: Can't find the thing I was thinking of now, but googling "psilocybin dmn" will yield some interesting reads regardless!