Hi fellow players and DMs. The game I'm about to run involves the party completing several quests among four kingdoms in the Feywild - Spring, Summer, Autumn, and Winter. I know the end goal for each of the large quests, but I need slightly smaller encounters lasting about 1 session to fill the gaps. An example is: 

A gate which blocks the entrance to the kingdom. When the party finds the man who usually owns the key to unlock the gate, he tells them that his keys have been stolen by a bandit. The players must track down the bandit and reclaim the keys.

I've planned that encounter to last roughly one session. So, what other quests and encounters can I place in the gaps? I've posted this thread on General Discussion and not on Dungeon Masters Only because I feel that players can be just as creative as DMs. Thanks! 

Depends on the level of the party?

Hags are always fun for higher up characters. (There's even some lower level hags). So the Hags could be doing something to manipulate the seasons.

A sea hag might want it to always rain, in hopes of flooding the Kingdom/Feywild.

A green hag might want Autumn, because that's when things die off (leaves fall, flowers wither, etc)

The annis hag wants Summer to burn eternal to watch things dry up and die.

The Bheur Hag wants winter, because that's what they enjoy.

Party level is 2-4.

Recover the Gems of the Seaons

• The party must scale a tall mountain (skill checks) to reach the Aarakocra, who have the Summer Gem - taken up high to be closer to the sun.
  • As they scale, they find a cave and encounter Galeb Duhr - who explain a young Grick has actually taken the Summer Stone from the Aarakocra and is further down the cave - and the Aarakocra do not feel comfortable because inside the cave they're restricted. You could even have them reach the Aarakocra who say it's in a cave, when they go the cave, the Galeb Duhr can explain it was a young grick who has it and gives them a general clue of where to look in the cave.
• The party must defeat a banshee (help put it to rest) to recover the Winter Gem which had been taken by the Banshee because it was as cold as her heart.
  • For a lower level, I would modify the Banshee. Drop her wail, maybe (unless the party is kicking her rump in). Could drop the HP as needed, too if the party is struggling. Could explain it that she's not a full Banshee. Alternatively, along the way, you could have the party find a beaten up house that was hers - and if they search it (make the DC whatever, or hide it in a specific place) they can find her diary - if they read the diary to her and remind her of how good she was - she will depart without a fight.
• The party must recover the Spring Gem from the center of a field of Shriekers, where it'd been lost.
  • However, the area also has become home to a number of Blights. The party can make some DC Dex checks to not awaken the Shriekers and potentially avoid the Blight fight.
• The party must recover the Autumn Gem from a Dryad who has taken it for safe keeping - and has forgotten her true mission (she was supposed to return it).
  • That portion of the forest has become corrupted and home to Ettercaps now, which must be defeated. When defeated, the Dryad awakens and recalls her true mission and returns the Autumn Gem.