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.
The best thing to do is to bury this placenta if possible. Many scholars are of the view that it is desirable to burry what comes out of the body of a human being, like the hair, nails and the like, and it may be that the placenta comes in priority over the hair and nails in regard to burying it.
Allaah Knows best.