Any kind of paper
The contents of lever arch files, ring binders and any type of folders, architects and engineers drawings up to A0 folded or open, A3/A4/A5, Foolscap, Quarto and other old sizes, continuous computer printouts, flip charts and just about anything else you can think of.
You do not need to remove paper from files or binders unless you wish to re-use them. Similarly paper clips and staples need not be extracted. Ideally any plastics should be removed to avoid contaminating the paper stream for recycling.
Paper does need to be dry.