4Game

I suspect something like this has been suggested before, but I couldn't find it by searching the sub.

The idea is simple: Every mushroom you pick up has a small chance to be of the psychedelic variety (maybe 5%?) and there's no way to tell them apart until you eat them. Maybe not fully realistic, but certainly entertaining. Eating such a shroom would slowly add trippy visuals to the screen and maybe even hallucinations that disappear upon interaction or proximity, e.g. illusory deer or enemies charging at you. The trip could last for 10-15 minutes.

Optional:

• Add buffs/debuffs to the magic shrooms, like decreased stamina regen and increased XP gain.
• Have different psychedelic effects for red and yellow mushrooms.
• Have "good trip" and "bad trip" effects. Which one you get might be random or it might depend on circumstances (e.g. eating a magic shroom while navigating a sea storm or being chased by enemies would result in a bad trip). Good trips would make everything extra vibrant and cause peaceful hallucinations, like a white deer grazing in the distance. Bad trips would have hostile hallucinations that can fool you into thinking you're in danger, like being ambushed by a swarm of illusory enemies.
• Add some way to tell magic shrooms apart from the rest. Maybe if you fall under their effect an X number of times, you gain the ability to distinguish them when gathering, perhaps by showing a different tooltip when you hover over them with the reticle.