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.
gummas gammas gums gummous gummose gamas gaums gamays commas gumbos gambas cumbias gambias gams goombahs goombays games comas camas gambs kumys camass gambes gombos koumis koumys kumiss caeomas cammies commies koumiss koumyss
commas shammas gummas summas mommas lemmas gammas mammas mas bemas hyphemias amass femmes gimmes comas mems rumbas ammos dumas hommos mums lamias limas pneumas lamas amias amas pimas mambas amahs lumas mumms gambas hummus nemas somas shammes shamas wammus gamas mamas masa zymase simas omasa mays maes mass moas biomass cymas gamays sambas moms camas loumas pumas caeomas limbas bimahs camass llamas emmys bimas zamias doumas nomas maws shammos
gummy gumma gum gamma gammy gaum gumbo