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.
grassy grass greasy gorsy gross crass grays grease creasy cressy cuirass gars carassow curassow gorse craws cross guars grows gores gaurs crazy grace greys grees goers koras gurus grues graze cress caress curacy kaross crosse guiros crease crissa kersey grouse gurries kerrias
grassy brassy morassy grass trass cuirass dressy prissy morass greasy creasy cressy crass harass frass brass wrasse drossy tressy