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.
mumms mums mummies mumus mommas mammas moms mammies muumuus mammeys mems mommies mammees momus mimes memos momes maims mamas memes mambas mambos mameys mamies mimeos mimosa mamboes
mumms humus gaums gammas gummas gimmes geums commas neumes pumas numbs summas mums moms sums mems doums lums dumbs loumas chums koumis shammes kumys ammos bums mumus lemmas emmys femmes gums heaumes hommos fumes neums rums pneumas hummus sumos hums doumas mommas dumas mammas wammus lumas shammas koumys shammos
mummy mumm mum mamma mammae mammee mammey mammie mammy momma mommy mumu muumuu umami