The Novalia 2017 items, such as the backgrounds, were for those particular days of Novalia and can not be gotten again ( like when the fishing pond first came out, the quilts and medic kits etc).
But Watery has a coloring contest that you can win one of the backgrounds at and I am sure at some time those items will appear for sale by members. I will probably put one up for a contest prize. At this point I am not gifting or selling any though.
Sadly, all you had to do was fulfill one quest from each sister per day during Novalia to get that days items -
HAPPILY, the time was reduced to every six hours per quest and some people were able to get multiples of the day specific items. Ask Gizzie if she is willing to trade or sell for any, she missed a wreath from one of the days.
Check out my BARTERTOWN thread as I will trade a past background for a Novalia 2017 background.