Well, my first instinct was Newfie mix.  Then it was Golden Retriever mix.  However, after looking again, I'm considering Border Collie or Aussie mix.  All the grass pics except the last one look collie-ish to me.  My Suzu's tail isn't anywhere near as glorious as Dahlia's, but her coat is very similar.  I don't have recent pics of it in all it's fluffy glory, but here are some when it was in it's growing stage.


 

 

 

 Don't know if that helps.