This is a discussion topic for the download "Xen Mushroom Prefab and Backdrop Room" by TheSeventh which can be found here
Download description:
Another bored afternoon and an experiment with vertex editing later and here you are. Should be pretty simple to find/replace if you want to re-texture it.
Includes bsp for Sven Co-op, J.A.C.K. .jmf and .rmf
If you use it in a map please just mention where you got it in a readme or something, idk it's 2022.