I heard a (highly suspicious) tale of origins that it was about the War of the Roses, and that it was originally:

Rose, Rose, Rose, Rose
Shall I ever see the red?
I will, merry, at thy will, sire,
at thy will.

(Supposedly being the words of a knight simultaneously contemplating a rose in his garden and his desire for Lancaster to win as he's being called to war.)

The follow up verse was SUPPOSEDLY originally:

Ding dong, ding dong
Wedding bells on a September morn
Carve thy name on a moss cover stone,
A moss covered stone.

(This being the wedding to end the war over the bodies of the losers.)

We atually sang the second vers in this manner, but the first was:

Rose, rose, rose, rose
Shall I ever see thee wed?
I will marry at thy will, sire,
At thy will.

Cute story. Probably nonsense.