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.
cash cashew cashoo cashaw gash cosh coach cache catch kasha cushy cuish quash cachou catchy cushaw gosh gush cooch couch cutch gushy ketch
ash mash deash fash hash cash gash quash lash bash leash gnash pash rash sash dash wash sh