Perry keeps a variety of items with him in large boxes held together with string. A lot of them are journals, letters, drawings, cards and other memorabilia. He has letters from his sister encouraging him to be better than his brother and sister, who committed suicide. He always has a letter from Floyd, who analyzes the letter for Perry, indicating that it's his sister that has problems, and not Perry.
One can tell from this that Perry is a pack rat who long to hold on to the past. Perry's childhood was full of abandonment, death and crisis. Perhaps he feels that if he holds on to these items, he can hold on to some of those people from his past.
The letter from Floyd show how much Perry is looking for acceptance (and may lead to why he hooked up with Dick in the first place.) Though the letter from Perry's sister is well-meaning, Floyd spins it so that it seems as though Barab is the one with the problems and Perry isn't doing anything wrong. From a childhood where Perry never knew who was going to be around, this acceptance is critical for him.