Requires ASJCore

What this mod does:

Prevents any mobs from spawning on blocks of mushrooms, trees, and leaves.

What is the problem, and how can it be useful:

The mob spawning system has a limit on the number of mobs (if you don't go into details and speak very simplistically). When mobs spawn on trees and large mushrooms, you may not be able to see them, or it may be difficult to reach them (if they are inside a tree, for example). This makes it feel like there are few mobs around you, and the speed of their appearance suffers.
In other words, the mod simply fixes the strange behavior of the mob spawning system, which results in improved gameplay and makes finding and interacting with mobs a bit easier.

You can see examples of bad spawn mobs in the Images section.

Note: There is another mod that was the inspiration for No Mob Spawning On Plants. Namely, No Mob Spawning on Trees.
There is no 100% confirmed information, but it seems that on version 1.7.10 this mod just doesn't do what it should. During testing, mobs continued to spawn on trees and mushrooms without any changes. Working with the config didn't lead to anything. So we will assume that the mod does not work as described. And in any case, No Mob Spawning On Plants is much smaller and simpler if someone only needs to fix the described problem of spawning mobs.