UW mom, yes flowers are a great idea. First check and see what her sorority's official flower is and send her something with those in it.
My house was the red carnation, which we were never too excited about, so my mom sent me flowers with red carnations and then assorted purple and gold flowers.
I'm not too sure about a good flower source. Ballard Blossom is near by, i hear they have some nice things.