George White was Phineas' pen pal. Phineas last saw him when he was 10. About a year prior to the events of "Road to Rhode Island", George sadly died of cancer and his parents had to move house and leave him behind.
While Phineas, Isabella & Adam was visiting George's parent's house, Adam discovered the body and didn't realise who it is, but Phineas discovers the body as his long-time pen pal George. Phineas was utterly devestated and dismayed that George has died and angered that his parents had to leave him. Thankfully, Adam & Isabella comforted Phineas and suggested to him they can give George a proper burial, which Phineas accepts.
So Adam, Phineas & Isabella goes to the cemetery and gives George a decent burial after Phineas finishes his speech. Phineas described George as "kind, polite, loyal and a great friend" and really liked him as a brother figure.