It’s graduation month. High school seniors are going off to college, and many parents are figuring out how they’re going to pay for an increasingly expensive education. The schools, on the other hand, aren’t all as cash-strapped. This week, USC got $25 million from trustee Rick Caruso to start a department of head and neck surgery. And Harvard, already the richest university in the world, received a $400 million donation from billionaire John Paulson. Where do big donations to already rich (and expensive) schools go?