Oops, it doesn't look like 'Park Open day' is a national day..

Other days

gum

Gum Day
bow tie

Bow Tie Day
gallery

Gallery Day
china

China Day
girl friend

Girl Friend Day
cuddle up

Cuddle Up Day
pumpkin

Pumpkin Day
tell a fairytale

Tell A Fairytale Day
blanket fort

Blanket Fort Day
fiancee

Fiancee Day