Disclaimer: I am not a doctor, please do not take this advice as infallible and especially please do not mix medication that is self administered based solely off of the following paragraph.

I don't think OP is suggesting they be taken at the same time. The answer to the question however is that would depend on the stimulant being ingested. If it is an amphetamine like adderall, there isn't that much cross interaction in their pharmacology. Adderall (amphetamines) in ADHD medication based doses primarily act in increasing dopamine in between neurons while psilocin is primarily acts on serotonin and its receptors. While there might be some compounding sympathetic nervous responses at standard therapeutic doses it is unlikely to cause any noticeable side effects.