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.
copras coppras coprahs copperas copers copperahs coppers copiers coopers capoeiras capers cooperies capris coappears cappers cuppers cuprous cupreous koupreys gapers caprice gawpers keepers kippers guipures quippers
coppras copras heapers loopers cappers knappers rapers lepers coprahs prays hopers cuppers praos pars gippers hypers prase papers praus copperahs gawpers coppers capoeiras pipers capers japers nippers coopers soapers peepers weepers yaupers supers shoppers shapers tapirs chippers wipers dippers whoopers whippers diapers toppers loppers spars tippers wrappers dupers rippers sappers kippers reapers cyprus zappers mopers sprays lappers vapors jeepers leapers operas hoopers vipers poppers gyppers capris keepers pros copers paupers copperas aporias beepers hoppers purs gapers apres proas paras lippers rappers nappers apyrase lopers boppers apers peppers sopors mappers spurs moppers zippers sapors repros quippers sippers ropers tapers cypres topers spireas uppers whappers diapirs whiprays whoppers dopers cheepers choppers tappers shippers yappers suppers yawpers
coprah copra coappear cooper coopery coper copier copper copperah coppery coppra