Today is the last day to do the Scholarly 'Shroom quests (add up to 350 coins per character), to read Developer Letters and get rewards for them (add up to 150 coins per account), and to collect and open 10th Anniversary Commemorative Boxes (can give up to 50 coins per character), to use the 10th Anniversary buff, to enjoy the item rain in the Festival map, to fight Pink Zakum, to eradicate Ikuras, or to prove the mastery of Pies over Cakes.
The shop will remain open until June 24th. Armor boxes might also keep dropping until then. That's what it looks like from the v162 Update Notes, but it could also be a typo.
Leaves will continue to drop until June 9th, but you'll have to talk to Cassandra (after the maintenance on the 3rd) to trade them for coins.
Don't say you weren't warned!