The hallucination affected by psychedelics such as mushrooms isn't what you might expect. It's not a fully synthetic kind of "i now see an object that is not actually there". There won't be a floating pink elephant in the middle of the room.
Instead the effect at most normal doses (3.5g) is more that the walls and floors seem to take on a slightly ephemeral breathing characteristic. You may see patterns in things of varying complexity and intensity. The patterns may seem to shift and meld into eachother in a kind of loop... Psychonaut wiki[0] has several approximations of varying quality, a lot of the gifs in particular (the cat lying on the couch and the wolf drinking) resonate with me.
Sensory input can also include audio hallucinations, as well as perceptions that are simply normally filtered out of our experience by our brains--a sense of the organs inside your body, or the teeth in your mouth, or whatever.
A lot of the effects are mental, prompting often amusing and revelatory departures from your normal thought patterns. Everything old is new again. You may find yourself deeply examining the complexity of your hands, or the bizarre fact that we're not always "like this", or in deep awe of the staggering complexity of civilization or the chemical machines that are our bodies. That kind of thing.
The realization that we collectively have no idea what we're doing here, that a whole lot of what we believe to be real and permanent is imaginary and temporary, and that there are no rules to life, no winners, that we should take care of nature and each other, and that you should follow your muse to do what you find interesting and beautiful.
Media portrayal of this varies but some shows do hit it quite on the head, actually Mad Men has an interesting trip episode that understates the visual component and emphasizes the mental[1]. Broad city's was particularly colorful and fun (S4e4, full ep. isn't on youtube).
Some media can give you a bit of a taste of the experience, others grossly exaggerate it or flat out misrepresent it. You know how it goes.
[0] https://psychonautwiki.org/wiki/Visual_effects_-_Psychedelic...
[1] https://www.youtube.com/watch?v=GpWlKCfSPcU