The willow seems to have been associated with regret in most folk songs that I know:

The willow tree will twist and the willow tree will twine
I wish I were in that young maid's arms that once held this heart of mine
(The seeds of love)

For he swore he'd never deceive me and I like a silly believed he
As the moon and the stars so brightly shone over the willow tree
(The weeping willow tree)

The there's All Around My Hat of course.

Another dance sounds like a good idea. Nothing too energetic though - I am feeling very mellow. So how about a bit of Playford - four couples for Newcastle. Can the musos handle the tune? Would any of the ladies like to dance with me?