One site I post to offers writing challenges. Recently, the challenge was to create a Tautogram, which is a poem where every word starts with the same letter. Here's what I came up with.
Ravenous ravens rising rushing
Rivers running, rippling red
Regal rulers, raging rivals
Righteous roars round region ring
Retreat rejected, ransom refused
Rage requires ruintion replete
Rotting renmants reddened realms
Regiments rest, reaching repose