When Kent Weeks was excavating KV5, which has been identified as the tomb of several Rameses II sons, a skull was discovered, along with several other human bones. The skull had a large gash in the forehead. It wasgiven a wild guess that it may have been the skull of one of Rameses' sons, but that was only a guess. As far as I know, the mummy of Rameses' eldest son has not been discovered.
Although KV5 has quite a few burial sites, they had all been looted and emptied in antiquity.