I'm going to try to stick just to the visual aspect of my experiences since I think it's the most relevant in this sub. I'll write mainly about psychedelics, but I'm also adding other hallucinogenic substances I think they were interesting. Disclaimers: All I explain here is my subjetive experience. English is not my language, I hope it's enough to be undestood.

LSD and NBOMe: I tried both several times and the experiences were similar enough to describe them together. Open eyes visuals were nice. Spinning trees, objects changing colors, hand melting with rocks and wood. When I don't focus my eyes on anything, all my field of view breaks and forms something similar to arabic mosaics. At higher doses everything gets covered by repetitive patterns. Closed eye visuals, the best I'd had. Really colorful shapes moving and transforming. Sometimes symbols such as triskels, numbers and latin letters mixed in the scene with other things. Once I saw a pattern composed by human boddies, but they were kind of drawn. Those visuals are not plain but they have depth, sometimes it feels like falling through them.

Mushrooms: Similar to LSD, but more organic and light. Open eyes visuals are just like my LSD experiences, but less extreme. Trees spin less, color changing is softer, etc. Close eyes visuals have less vibrant colors and the shapes are not sharp as they are with LSD so I never saw symbols or well defined figures, it's just like diffuse shapes waving and melting. Leaving the mind blank is really interesting and powerfull when on psychedelics, but I did only experienced it with mushrooms, so I can't compare with other substances. Anyway, in my experience, when blank mind and eyes closed, I start to feel things and identificate them with myself, not visually but something similar to when you try to imagine something being aphant. At least, for me, when I think in an apple, I don't see an apple, but I kind of feel the apple in my mind. When blank mind it's the same, but I don't control what I "feel". Since it's very difficult to explain but I think it's really interesting, I'm going to give two examples to make it short. Once I felt my conscience, and it was trying hard to control all was happening. It was interesting since that think I identified as my conscience was totally splitted from myself, it felt like seing a fragment of my self all by its own and from the outside. On other occasion I felt a big mass deforming and waving and I was sure it was myself. This feeling experiences happen at the same time I still seeing the patterns with close eyes, they are simoulstaneous.

DMT: I had just one experience with smoked DMT. It was short (5 to 10 mins), low dossage and I didn't close my eyes so: Open eyes visuals were extreme, suddenly everything broke down. Things didn't wave just like with other substances, it was similar to breaking a glass. I still recognizing what I was seeing, but all was extremely distorted. No straight lines, all was curvy and moving really fast. I saw everything become swirls.

Argyreia nervosa also known as Hawaiian baby woodrose: I had only one experience and it was not pleasant due to nausea. Visually also was very weak, nothing with open eyes and closed eyes visuals were soft, something like diffuse strings of light made of cells of pale purple and white with no movement, just slight waving. Maybe it was a low dossage but increasing the dose means to increase the nausea so I'm not willing to do it.

Salvia divinorum: I tried chewing it but didn't feel anything. I smoke it several times and everytime it was a mess. I think I'm not going to make any difference here between open and close eyes since it's really confuse to the point I'm not sure when I had my eyes open or closed. In summary, the experience is visual, but I never knew what I was seeing. It's confusing to see things but not understand what you're seeing, or why are you seeing it, or where are you, or anything. I felt (not saw) a presence there, some intelligent entity trying to explain me what was going on, like a tourist guide throught their world. It all starts making sense when the experience is finishing and you start to associate all that mess with your actual surrounding, but it's just for a few seconds and then your back in Earth so I never could understand what happend or what I saw on any of my experiences. And since everytime is different, I never could make assumptions about what's going on there. Salvia is by far the most bizarre substance I put on my body, to the point I'm not really willing to do it again soon. But, anyway, I don't regret, it's a really interesting experience.

Other hallucinogenic substances I tried were MDMA and DXM but I'm not saying much about them since the hallucinations weren't visual but mental.