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.
poppas pops poppies papas pupas popes poops popsy pappus popsie puppies pappies pips peps pups paps pipes peeps pepos pupus papaws papoose pappose pappous pawpaws pappoose
cuppas kappas chuppas nappas poppas koppas pas typps pass pappus quippus kapas paws repass spaes tapas copays nipas pips pupas repays sepias spas dopas tepas upas spays pias chuppahs pase apps cowpeas pays nappes pawpaws opahs pops lipase repps peas hippos peps papaws napas paps huppahs pups bypass papas capias shoppes
poppa poppy pop pappi pappy peppy poop pope puppy epopee epopoeia