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.
sypher sphere cypher sphery cipher sigher safer saver sever siver severe soever suaver suffer zephyr savvier
gopher sypher cipher cypher rougher weigher ephor higher cougher laugher nigher sigher sphery zephyr tephra tougher sphere shophar