Tupelo honey is honey from tupelo trees and it's great, and very rich and sweet.

IMHO, even though there may be a Southern tradition of throwing the ring in the water when an engagement was broken, that's not the meaning here. (I fell in love with the song first time I heard it, by the way, and never fell out of love with it....)

Anyway, the first time I heard it, I felt that the girl in the song had been in love with Billie Joe for years but to him she was just a friend, sort of a kid sister; and that they had just been talking and carelessly tossing grass stalks, sticks, flowers or some such in the water while they stood on the bridge and talked. It gave me an image of a girl for whom every moment with the guy she cares about is precious, even though it isn't the same way with him.

For me it seemed like a natural thing to toss bits of something in the water when you're standing and talking on a bridge. And it gave the image of him treating her like one of the guys.

And the song so clearly implies that Billie Joe's death is a great blow to her but she hides the fact. So I think she never wanted anyone to know she loved him.

I know that's a lot to read into the song, but that's how I've always interpreted it.