Howdy!
With LSD, I always behold the Singularity, the Platonic One, the Ouroboros as either a dragon or a Weiner dog eating its own tail, before it devolves into a heavy rundown of my psychological state; it's like two year's worth of therapy compressed into 2-3 hours..... A friend of mine and I encountered Leaf Gnomes once (long story); we didn't stop seeing them for a year and a half after that. (It may just look like leaves in the wind to you, buddy – but you gotta believe me – THERE's SOMETHING THERE!!!)
With DMT, initially I'll see shifting non-euclidian geometry, which will then form into remarkably mundane scenes like the corner of a gas station bathroom where the mop and bucket are kept (that was my 'vision' last night), cracks in the sidewalk, etc. If I focus on any one thing, I'll see that it's comprised of gears. Gears seem to be an ongoing motif with DMT. Once I encountered two stick figures, a man and a boy, who inside their spherical heads I could see an assortment of clock gears and oddly shaped mechanical parts that looked like watch bits and pieces. These pieces were just sitting there doing nothing, as if they'd been haphazardly placed into a box for storage.
The one time I injected DPT intramuscularly, I perceived the souls of the unborn. They were wide-eyed naked children of about 2 years of age who lived in a lake beneath the surface of the earth in the area where they sought incarnation. They had to watch and wait for a body to enter. They all took notice of me and were amused.... When I was coming down, I heard this low-pitched hum/grumble that seemed to emanate from the center of the Earth. Like the bass guitar player in a rock 'n roll band, it was the unheard 'glue' that held it all together. I felt as though it was always there, but because of the limitations of human hearing, I normally didn't perceive it.
On all psychedelics, sound and its accompanying visuals as an undulating octopus tentacle composed of waves instead of suction cups, which stretch out to connect with various things and people for the purpose of communication, is a recurring theme for me.
Good question!