We do not know what the books were about, and we can only form some guess as to what the parchments were. Paul had a few books which were left, perhaps wrapped up in the cloak, and Timothy was to be careful to bring them. Even an apostle must read. . . . A man who comes up into the pulpit, professes to take his text on the spot, and talks any quantity of nonsense, is the idol of many. If he will speak without premeditation, or pretend to do so, and never produce what they call a dish of dead men's brains—oh! that is the preacher. How rebuked are they by the apostle!
Read a bit more on Justin Taylor's blog, well worth it.