I've taken a list of English words, and examined each of them to see what they sound like (using the PHP metaphone function). This page lists the most common metaphone codes, along with their words. You can also search for a word of your own, and see which words sound similar - and which ones rhyme, and which ones alliterate.
mummy mumm mammy mommy mum mammey mumu mamey mamma momma mammie mammee mammae muumuu mom mem mim maim mama meme memo mime mome momi
gummy dummy chummy yummy rummy tummy mummy umm jemmy shimmy jimmy hammy tammy mumm rammy tommy whammy gumma mommy summa emmy pommy fumy mammy gammy commy chammy immy gemmy jammy mammey shammy
mumm mummy umm mum summa mammey gumma gummy mamma mammae mammee mammie muumuu mommy rummy mammy summae momma tummy mumu dummy yummy