How the squash event works: where to get seeds and souvenir weapons, how to grow a large squash of high quality, what drops from the squashes, and a few observations from practice.
One more of the oldest events in the game, and the later the chronicles it is held on, the less interesting it is to people. Unlike most events, this one suits even C4, because there is nothing from higher chronicles among the rewards, neither life stones nor Dino weapons. And on C4 this event is really relevant, because you do not have to tediously level a soul crystal to level 10: you can get it straight from a squash.
First I will tell about the principles of this event and about the rewards, and then about how to grow big and beautiful squashes.
The point of the event is that little jugs will drop from mobs, which serve several purposes: they can be exchanged for squash seeds, they can be exchanged for souvenir weapons, and with their help a squash is grown. Seeds and souvenir weapons are obtained from the cat NPC that stands in all the towns during the event. A weapon costs 50 jugs, a small squash seed 10 jugs, a large squash seed 50 jugs.
A seed can be planted by clicking on it, and right after that a little squash appears. It has to be fed: take it in target and use a jug, and so up to five times. After that the squash grows up and can be broken.
Small squashes break from one blow with any weapon, but the reward from such a squash is tiny too. So it is more profitable to grow large squashes. But here we run into the fact that an ordinary weapon will not break such a squash; that is exactly what the souvenir weapon is for. And even with a souvenir weapon you will not manage to farm a large squash alone: for that I gather at least four characters of level 40-50, buff them with haste and start growing squashes.
We put the seeds and the jugs on the quick panel. After the seed is planted and the little squash has appeared, we take it in target and "water" it from the jugs. After each "watering" the squash "responds" to the action: either a little red cloud appears above it, or blue rays come out of it. If out of five waterings there is more red, a large squash of low quality grows; if there is more blue, a large squash of high quality grows.
The low quality squash is all dirty-looking, and the reward for it is worse. And the high quality squash is all smooth and yellow, and the reward for it is better. You have one minute to break a grown squash; if you do not manage within this minute, the squash disappears.
Rewards
These are various buff bottles: 
Greater Magic Haste Potion, 
Greater Swift Attack Potion, 
Greater Haste Potion, 
Quick Healing Potion.
The first of these bottles is for acumen; it can even be knocked out of mobs, so it is the least interesting one. The second (violet) bottle is a level 2 haste buff: it lets you do without taking a prophet along for haste and buff it from the bottle. The third (green) bottle is plain wind walk, that is, a buff for running. Both the second and the third bottle can be bought from the Merchant of Mammon for ancient adena in the week of the Seven Signs victory, so they are not scarce either.
But the fourth bottle, the so-called "quick", is the most valuable item: it instantly restores the character's HP, and such a bottle can either be crafted in a castle or got from the event. Quicks often save you in a critical situation, so I always take them with me either to raid bosses or to the dino island.
Besides the bottles, weapon and armor enchant scrolls drop from the squashes: 
Scroll: Enchant Armor (Grade D), 
Scroll: Enchant Armor (Grade C), 
Scroll: Enchant Armor (Grade B), 
Scroll: Enchant Weapon (Grade D), 
Scroll: Enchant Weapon (Grade C), 
Scroll: Enchant Weapon (Grade B).
B-grade armor and weapon scrolls drop only from large squashes of high quality. The drop from the squashes also includes soul crystals of levels 9 and 10, which is of no value for players of the Interlude chronicles, because these crystals are sold at the Luxury Shop, whereas on the C4 chronicles there are no such sales, and there you can stock up well on soul crystals from this event instead of bothering with levelling crystals on mobs.
And the last thing that drops from the squashes is A-grade crystals; very few of them drop, 4 at a time, but if you have many seeds, you can gather these crystals too.
Observations
- The inventory fills up very quickly with all sorts of enchant scrolls, especially D-grade ones. On Interlude players even refuse to pick up D-grade scrolls, and many of them lie around after the event.
- Only one item drops from the small squashes: one quick, one wind walk and so on, so it is not worth bothering with the small ones; go straight for the large.
- To feed up a large squash you need up to five jugs, but it does not have to be exactly five. If you failed the first three feedings, that is, a red cloud appears above the squash after each, the program may understand that you are a hopeless loser and give you a large squash of low quality already after three feedings. In that case the number of different items in the reward will be sharply limited, to one or two.
- It has been noticed that soul crystals drop better from squashes of low quality.
And the last thing I would like to note. I have seen the squash event in two implementations. The first is what I told you above. In the second variant the reward includes recipes for B-grade weapons and armor; that was on the Interlude chronicles on rather well-known servers. Among the weapon recipes the 100% recipe for the Great Sword prevailed, and among the armor recipes the 100% recipes for Avadon gloves and boots, with the word Sealed added to the recipe names, that is, such recipes do not drop from mobs. And the admins claimed that precisely this variant of the event is the most correct one. Yes, and some Rice Cakes dropped from the squashes there too: these cakes restored both HP and MP, a little, but instantly and, as far as I remember, without a cooldown.