Everyone has given u some great ideas, I thought maybe since she'll be sharing the room ... earphones ... u know the noise reduction kind ... so even if she isn't listening to music, she can still drown out the noice around her...
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Maybe a matching eye mask, u know the kind to block out sunlight & anything else she might not want to see lol...
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You could even get a nice box and make a..... Everything You Need to Survive in a Dorm Box.......Dorm Survival Kit ... (I know corny but I'm themey when it comes to gifts lol)..
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It doesn't have to be too expensive just a bunch of stuff along with the top two, here's some other ideas for the box..
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Playing cards (solitare if the power goes out)..
Movie passes (need an escape)..
Ear plugs (if you don't get the earphones)..
Roll of Quarters (for the vending machines)..
Map of the City (if it's a new place to her) ..
Your number in a sealed tube (call in case of emergency)..
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Just an idea .....
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Angie..
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I'm the yin to Carlos yang .....

A plant would be nice, too -- would last longer than flowers and keep reminding her of you...
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But if I were you I'd get her something really unusual and funky. Check out some yard sales and antique shops. So many people furnish their dorm rooms with plastic crap from Target, it'd be nice to give her something a little more meaningful with some history behind it. A cool old tray or little jar or a painting or an antique toy or an old advertisement sign. If you go browse around I bet something will strike your fancy and remind you of her. I hope that helps!..

You can never go wrong with beautiful flowers. And dorm rooms need any help they can get...
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To make it more personal and romantic, try to find out beforehand -- without spoiling the surprise -- what her favorite flowers are...

A pet salamander, a pet rock, a Chia pet. A Venus flytrap. A keg. A disco ball (but NOT a strobe light or a lava lamp, puhleeze). A karaoke machine. A chocolate fountain. A cappucino maker. A Snoopy sno-cone maker. A bong. A goldfish. A big pickle jar full of quarters. A pair of fuzzy slippers. A body pillow. A cozy afghan or blanket. A gumball machine. A Magic 8 ball (I made al the important decisions of my college years based on the advice my Magic 8 ball dispensed), a Slinky, a set of Play-Doh (D'oh!), a game of Mousetrap, a MagnaDoodle, an Etch-a-Sketch...

Hm, flowers were my first thought, too, but might come across a little more "I like-like you" than you may be ready to be right now. Thinking back to my own dorm experience, I'd say specialty teas or powdered cappuccino (though I wouldn't drink that anymore) that you can make in-room to help stay up late or wake up post-party, her favorite snack (procrastination via food or beverage is key), flowy ink pens in different colors for maximum doodling while doing homework, etc...