Yes. Located at the foot of most modern caskets, there is a little clear tube (glass or sturdy plastic) that screws securely into its own little slot. Before burial, the funeral director or embalmer will unscrew this tube and insert a slip of paper into it. This paper will identify the remains, the funeral home that took care of the decedent, the date of the burial and any other important information.
This is just in case any future identification of the decedent is ever required (following exhumation, catastrophic flooding, or another natural disaster that dislodges the casket and/or remains).
Interesting tidbit: The funeral director will most likely write this note in pencil as opposed to pen. Pencil lasts much longer than pen ink, and will not drastically fade when in contact with water.