When I was at primary school- in Essex, not Wales- we learnt a song in Welsh for St. Davids Day. This was 25 years ago so my memory of much about it is dim.
I have no concept of what the song is called, and don't speak Welsh but can still recite the whole thing from start to finish. And it was just being sung in the wedding scene in Stella.
I'm now really curious as to what it is. I vaguely remember being told it was about a farmer maybe?
If it helps, and it probably won't, here is my phonetic spelling of the first verse:
Me seeth voocan en y yank fole
Ver verken er ver fancy
Begeen begal y gwenythgwen
Erk erral erral vandrith
Anyone?