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.
copperas copperahs coppers coppras copers copras coappears copiers cappers coopers cuppers coprahs capers capoeiras cooperies kippers quippers capris gapers gawpers keepers koupreys
copperas operas coappears knappers rapers loppers vipers lappers capoeiras lepers jeepers praos gawpers kippers peepers papers nippers praus hoopers hoppers perse pipers copers coppers prays coprahs apers appears copperahs weepers yaupers toppers shoppers shapers tapers chippers wipers dopers whoopers whippers zappers ropers spiers tippers reappears soapers loopers rappers sappers diapers beepers supers mopers speers cuppers proas gyppers paupers cappers paras prase coppras peppers gippers peres lopers heapers piers hypers japers mappers gapers copiers keepers hopers coopers leapers lippers peers poppers peris capers moppers copras quippers speirs spears boppers sprays nappers zippers wrappers rapiers pears sippers reapers tappers rippers uppers suppers whappers whiprays dippers whoppers cheepers dupers choppers shippers topers yappers yawpers
copper copperah coppery capper coappear cooper coopery coper copier coppra cupper