This Nature Assets pack 2 has 15 different types of leaves, 7 types of trees, 4 shrubs, 3 rocks, and some grass and leaves. You can use these assets in your projects however you want.
NOTE: for FBX particle settings and some textures could be altered in the FBX file
Also, Check out my Free Nature Assets pack 1 with 5 rocks, 4 grass and a twig on (https://www.cgtrader.com/free-3d-models/various/various-models/nature-assets-pack-1-grass-rocks-twig)