The Rainbow Oak trees from the Twilight Forest mod. Just the trees...but in the overworld. That's it. That's the mod.
(By default, they are found only in vanilla Flower Forests. This can be changed with a datapack if you know how. I would like to eventually get around to offering one here for people to use and/or edit, but I may never get the time to.)
You can also find this on Curseforge...not that you'd want to. :P
Past versions of this mod:
https://www.curseforge.com/minecraft/mc-mods/rainbow-oak-trees (was for 1.10-1.12, no longer on CF)
https://www.curseforge.com/minecraft/mc-mods/rainbow-oak-trees-2 (MC 1.17-1.19.3)
Special thanks to Benimatic for the original Twilight Forest mod, as well as the current team maintaining it!
