How do you cash a US Savings Bond if your name is not on there?

My parents bought me a number of US Savings Bonds when I was a little kid in anticipation of giving them to me as a present when I matured. Well I recently tried to goto a bank and cash them and I was out of luck because not all of the bonds have my name on them, some of them had my mom and some of them had my dads name on there. Some even said PUD and my name. Any advice??