Melatonin is already in your body, it's a hormone that aids in inducing sleep and keeping our bodies in a regular sleep cycle even for us shift workers. It can be taken as a suppliment and for what it is worth the neurologist I'm seeing is a big fan of it!
If you sleep sounder, you reach and maintain REM Sleep easier and longer, which induces dreaming - sadly, anything I have read doesn't state it helps you recall dreams any better with the taking of melatonin suppliments. So, I'm like you, I love to dream and try to recall as many as possible, even lucid dream - that time when you are nearly awake yet still sleeping and you can direct your dreams to some degree - neat when your dreams come out the way you'd like, remembering them is much easier when you have imput.
I can lucid dream until someone or some situation causes me to have to make a calculated decision, like deciding on multiple choices at an intersection, or doing some kind of reading or math problem - then I wake up almost every time.