Here's a poll question that likely has not yet been asked...
If you don't know the phase of the Moon on your birthday (and I'd be surprised if anyone here already did (aside from those who looked it up in the chatroom)), you can find a site
HERE that can provide you with an answer. Just input a month and year on the right, and look up the Moon's phase on the calendar.
And if you end up being between to of the phase definitions, use your best judgement to pick which one you're closer to.
I was born under a Third Quarter Moon, by the way.