Roth IRAs and Savings Bonds

Can I invest my Roth IRA funds in Savings Bonds? Tom's response The Treasury says you can put Savings Bonds in a traditional IRA but not a Roth IRA. Even then, however, it seems mostly theoretical rather than practical, because you also have to find an organization that will act as the IRA Trustee, and although there must be some, I've yet to identify one.