I don’t really have a very particular species that I have seen after dreaming of seeing yet, but here’s a few that I have seen:
I was very lucky to be able to finally travel to see my dad’s side of the family a few years ago, and while walking somewhere I happened to notice a threadsnake of some kind crossing our path! I had never seen one before or since, and it was very interesting to see just how small their little faces are 
. My mom didn’t even believe it was a snake at first.
During that same trip we visited an “abandoned” park facility and, while walking around and looking around for fauna, and saw what was likely a Blue-Headed Tree Agama in a tree. I ran to tell my dad « j’ai vu une tête-bleue! »
The reason I got so exited was that my dad had always told me stories about these lizards (tête-bleues) and how they were viewed in local superstition, and I had finally seen one for myself! (I unfortunately couldn’t snap a picture).
Lastly, since learning about them I had wanted to see a Giant Leopard Moth, and at a summer camp in Minnesota I found one on a walking path. The poor thing was dying, but I’m glad I was able to see one.
A cool individual I’ve seen would have to be this blue-eyed periodical cicada I spotted in 2021.
One species I dream of seeing that is relatively rare is the Leatherback Sea Turtle.