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

Other days

kale

Kale Day
lumpy rug

Lumpy Rug Day
hannah

Hannah Day
chocolate milkshake

Chocolate Milkshake Day
bow tie

Bow Tie Day
boy friend

Boy Friend Day
healing

Healing Day
pumpkin

Pumpkin Day
girl friend

Girl Friend Day
unicorn

Unicorn Day