I am totally unhappy with my voice. In my opinion, my voice sounds like Kermit the Frog. I have practiced using a stick between my teeth, but this only helps with articulation.
Is it possible to train my voice to improve its tone and clarity?
Go get some classes on singing... Talent is really a small part of it, and most of the rest you can learn. It can be harder or easier, but you can probably have a richer sound if you study with someone who knows what they're doing.
If you can't afford a teacher, there are tons of videos on the internet about breath support and intonation, that can help you a long way, but I strongly recommend you find help, as you can damage your voice if you do something wrong...