Following the example:
https://docs.unrealengine.com/latest/INT/Resources/Showcases/Stylized/Materials/index.html (Foliage Material)
I got this problem:
https://dl.dropboxusercontent.com/u/28070491/UE/Forums/FaceToCamera/ErrorShadows.jpg
the planes/materials are two side and don’t cast shadows to self, only shadows between the planes/materials as you can see in the screenshot.
Files: https://dl.dropboxusercontent.com/u/28070491/UE/Forums/FaceToCamera/Files.zip
Answerhub post: Face to camera wrong shadows - Rendering - Unreal Engine Forums