Found some Mass. bonds (because it's my home state, so tax-free for both federal and state) yielding 6.43% just now, with expiration date of 2029-05-01 and with credit rating of AA+
http://massachusetts.municipalbonds.com/bonds/issue/914440KJ....
Also can also buy some REITs with annual high-dividend yield of 17% such as AGNC or NLY. These are a bit riskier due to fluctuating principal out on the open equity market. However, can mitigate this risk by owning ITM calls prior to ex-dividend dates and capture also run-up profits.