I was sorting through my mom's change and seperating it for her when I came across a weird coin. After looking at it I noticed it was a 1799 Britannia coin. Never heard of or seen one before. With my luck it's either not worth anything or fake.
By Britannia, do you mean the image of someone seated, helmeted, holding a spear? That sounds like the old British penny. If its a vey large coin, dark brown, maybe that's waht you have.
Doubt it it would be valuable, but would be nice to have something that old.
But check a coin catalog, at a book store or a library, if there is not an on-line source.
Well, I think you can rule out it being a fake. You could probably find out more doing a google search. I did a quick one and came up with this site that might help you.