You raise good points, and I agree with most of what you say.
Of course being mentally ill doesn't necessarily make the person dysfunctional. The fact that society has created a certain image of what mental illness is, is a different topic. Still, someone who experiences vivid hallucinations (provided these are not caused by stress, or lack of sleep, or a seizure or anything like that) has a mental illness. I never said this made them unstable, but it's still not "normal."
The visuals on mushrooms, for the average dose (1-3 grams), are usually things like walls breathing, trails left after movement, people's skin looking like it's made out of plastic or made out of layers, things looking like they have faces, voices sounding higher or lower in pitch... I would call them
distortions rather than hallucinations (nothing is created that wasn't there before; they just distort and move).— For vivid hallucinations on mushrooms, you would have to take a rather high dose: 4-10 g's; most people won't go that high. But that's beside the point, my point is that the hallucinations don't persist once the drug wore off.
If these people were having vivid hallucinations on an average dose of mushrooms: A) these were very potent mushrooms, or B) they were laced with LSD (the two drugs mixed together have an effect much more potent than either alone).
I think you misunderstood my what I meant: my point was not that, since I've never done any of the drugs that can cause such episodes, I'm not hallucinating; my point was that, if I
am hallucinating, it's not likely to be caused by the few and far in between occasions in which I've done mushrooms. So the fact that I was on them during one of these weird events is irrelevant in regards to the other events.
You are right that certain types of hallucinations are normal: Maybe you think you hear the voice of someone you live with calling you. Or you think you see something out of the corner of your eye. Or your dog keeps telling you kill Edward Norton because he's the son of the devil and about to stop the second coming of christ. This is all normal.— but full-blown, vivid hallucinations are not.
The event that involved the mushrooms was, in fact a visual hallucination (I've mentioned it before), and does not involve ghosts or spirits: both me and my friends saw ourselves on a roller-coaster— then we imagined that everyone else was speaking with bubbles of sound coming out of their mouth— but that's not what's interesting here— What I find interesting about it, is that two people would "share a trip:" what would cause two people to, out of all the millions of things that could pop into their minds, imagine themselves in the exact same situation, without verbal communication? ... that's what I find interesting.
On the other incident (and this one does not involve drugs), I was at my house, going up the stairs, when I hear my friend go "ah!" (my friend was actually there, in case you're wondering

)— I turned around and, for a split second, I could swear I saw the image of a little boy, standing by him, holding his hand: it was literally a split of a second, and out of the corner of my eye.
When I asked him why he squealed, he said he just felt something weird on his left arm. We were both pretty freaked out, because, though he hadn't actually seen anything, he just felt "weird." ... I doubt there was an actual boy there ... what I find fascinating, again, is that we would both have that reaction. What causes shared experiences like these? How does this information travel between the two people? I don't know and I'm curious.
To me this is more a question of human perception and communication. A questions about the way our minds build a representation of the world around us, how they represent things they can't understand, and also possibly a question of information transfer and communication.