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

Other days

slime

Slime Day
ormille

Ormille Day
offer

Offer Day
polyamory

Polyamory Day
blanket fort

Blanket Fort Day
ruby

Ruby Day
chocolate milkshake

Chocolate Milkshake Day
believe

Believe Day
prosecco

Prosecco Day
youth

Youth Day