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.
maduro madre madder mature madeira muter metro mater matter midair mudder matier mutter mattery meatier moidore moodier muddier
maduro duro dour dura dure durr hydro odour pedro siddur
mad made maid maud maut mayday mead meadow meadowy amadou maumet