All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
According to the most preponderant opinion of the scholars putting green palm-tree leaves on graves is something peculiar to the Prophet because of the evidence that is reported in this regard. As regards putting palm branches stripped of their leaves inside the grave with the dead, this is something that the Prophet never did. Therefore, you must shun such an action. Moreover, the difference of opinion among the scholars is only regarding putting this kind of leaves on graves.
Allaah Knows best.