My DS likes his comforter from home (has used since he was five years old) so took that, no need to buy new.
We bought 2 new XL sheets sets. He only uses the fitted and only used one set all year, so the second wasn't needed. (I got it just in case he needed to change out quickly...like if he got sick on it).
Laundry hamper
Standing fan (already had at home)
Rubbermaid containers for under the bed: held shoes in one, linens and cleaning items in another, food stuff and medicine items in the third
bucket/caddy for shower items (he threw away before coming home...is was moldy....)
2 towel sets (but probably could have sent some from home) he lost his two bath towels and came home with one of someone else's.
hangers--he had very little drawer space so some clothes had to be hung up that normally wouldn't
Could not use extension cords in the dorm so had to buy surge protectors with long cords
micro-fridge was supplied, so no need to buy those things. They hardly used them anyway. Easier to walk next door to the Subway and Grille.
We also bought a metal bedstand/shelving unit at BB&B that went at the head of his bed for more shelving. After putting it together, it was impossible to take apart and got left behind at the end of the year.

He did use it. Hung is wet towel from it, had a place for his alarm clock and other items he needed right at hand.
area rug if the room is not carpeted
Here's the things that I bought that never got used: plastic bowls/storage containers/plates, paper towel roll, hand towels and wash clothes (only used the bath towels from sets), second set of XL sheets, 3-ring binders,
Things I should have sent: broom/dustpan or sweeper, air freshener (got some later)
Next year, my son is in a larger suite and will have more room (thank goodness as this year's room was tinier than mine was at school and I thought it was small) and may have room for some extra shelving. I already bought a set we're using at home and come apart easily, so expect to bring that.
Last year he didn't have a closet, they had wardrobes in the rooms, so a hanging bag for shoes or such was not usable. I think he's got a regular closet this year so we might invest in some closet organizers (or maybe not....).