What's Better- Bonds or Cert of Deposits?

I have been saving change for my grandkids and have over $50 for each right now. Our local credit union has certificates of deposit that can be purchased for children for as low as $50 minimum. Am I better off buying US Savings bonds or opening the CD accounts? The CD's would have to be in the childs name, parents name and I could also be listed... the problem is I don;t trust my daughter in law not to cash the CD's. If I buy bonds am I able to put them in my grandchildren's names and my name to make sure they don;t get cashed? We don;t have a lot of money, and I was never able to save for my own kids so I would really like to be able to keep building a small nest egg for my grandchildren.