to install the meshes correctly, do this:
copy all .material .mesh and .png files in to FeralHeart\media\objects\my_objects, except NutmegPlant.object
copy NutmegPlant.object in to FeralHeart\media\objects
Edit:
i forgot to mention, after that, you will find a new group called NutmegPlant at object or map maker. The models will appear correctly.
if it doesn't work, then try this.
the material names are not the file name.
to know the material name open the .material file in notepad.
and you can see the material name.