ANZAC day.

The ANZACs were the Australian and New Zealand Army Corps who fought in WWI in the battle of Gallipoli - April 25th was the day they landed. The holiday is there to commemorate the New Zealand and Australian soliders who fought, and those who died. I don't know about Australia, but in New Zealand (being the tiny country that it is) just about everyone has a connection to someone who fought (my grandfather and great uncle were both involved).
Every year there are dawn parades all over the country, where veterans gather (there aren't many left these days) and wreaths are laid, and the Last Post is played on the bugel just as the sun rises. They're not big, flashy ceremonies...

Red poppies were the only flowers that ever grew on battle fields, because they thrived in the loose soil disturbed by the bombs. While the flowers bloomed, the field became a sea of red, and not just from the poppies. Poppies are also the traditional flower of rememberance.
So every year on ANZAC day people put red poppies on the graves of their ancestors who died in the war, and the Returned Services Association sells little felt poppy pins on the street for a donation.

Oh, and there is a commemorative biscuit too, the Anzac biscuit, a golden syrupy rolled oaty thing, sort of chewy and crunchy at the same time, and it's delicious.