This very simple mod adds a config file which lets you control additional tall grass and fern spawning. The value for each config is the chance for each block in the world that a new tall grass or fern block will spawn on top of it during world generation. I don't know who would need to use this (besides the guy who requested it on /r/feedthebeast), but I might as well make it public access.
Do whatever you want with this mod, see if I care.
