watercolor girl

Can anyone help me with this.  I don't have any information except what is stated before. I bought it a a thrift store for 50.00 dollars.  when pulled out of frame its on paper ,but is taped onto a cardboard box of some kind, like the ones that they used for shirt boxes long ago. and there is watercolor marks on the cardboard like the artist was testing his/hers color pallet. It is signed mackenzie kinda sideways part of the way up on the lefk side in the grass.  Anyway any kind of information would be helpful, so thanks in advance..    Merry Christmas to All

Poor