The story of Lord Ganesha getting an elephant head is well known. I am interested in knowing what happened to the original head.
According to this site, the head is in a cave:
The head is in a cave known as Patal Bhuvaneshwar It is believed that Lord Shiva had separated the head of Lord Ganesha from the body and kept it in a cave. This cave is known as Patal Bhuvaneshwar. The idol of Lord Ganesha in this cave is called Adi Ganesha. According to the belief, this cave was discovered by Adi Shankaracharya in Kali Yuga.
But the site does not mention the specific Purana which contains the story. I am looking for the exact verses from the Puranas or any other scriptures that talk about it