[flabort]

Aha! A challenge! This is exactly the inverse of my style.
And congrats to the winner, and runner-ups. I'd like to see a deck built around each of those.

Design Process:

Spoiler

Ideas:
A spectral cat
A sliver that can return from the graveyard <-too mechanical, not enough flavor
A house that eats people
A fruit that talks and casts spells <- Like a wizard?
Some sort of ice elemental
A Madman who worships slivers and seeks to become one through magic
((Some card with cumulative upkeep - Put an age counter on ~, and another cumulative upkeep for some other effect - 1st round ends with three counters, 2nd 9, 2rd 21, 4th 45... add 1, double, add 1 more, pay for each. 5th 93, 6th 189...)) <-Definitely not top down
Someone who steals internal organs
Someone who plays magical bagpipes
Someone who has an instrument built/grafted into them.
A place where specific dead get buried, only for them to come back <- could be interesting, but too specific (mechanics)/general (fluff)

Lets go with talking fruit wizard.

Research:
Fruits don't talk, only two Magic cards even have the word fruit on them: Fruition, and Forced Fruition, neither of which actually involves fruit.
The word coconut derives from Cocos, meaning "grinning face". It is also a Drupe, not a nut, so is a fruit.
There are no cards with coconut in them, and only two with nut: Frankie Peanuts, and Nut Collector, neither of which has to do with talking fruits.
Wizard cards "channel mana into spells". Some can create or combine life.
Saprolings are plant lifeforms. So are Thallids. And treefolk. So are plants, though they are non-sentient.
Coconuts grow on coconut palms.

Brainstorming:
Seems that this could be a result of the Simic Combine, or be created by treefolk?
If it's created by a treefolk, it would need to be a token. It could then either be a saproling, or plant type.
This would then make the card itself a treefolk, and therefore a palm, not a coconut.

Would the treefolk act as a guardian to it's seeds, or more as a master?
If it acts as a guardian, it would have an ability to protect the tokens it creates. If it were a master, it would have it's own wizardly power.

Card design:

Palm gaurdian #1 - 3G
Creature - Treefolk
When ~ enters the battlefield, place 3 1/2 green plant wizard creature tokens named Grinning Coconut with "Tap: add one blue or green mana to your mana pool" onto the battlefield.
If a plant token would take damage, the damage is redirected to ~ instead.
~ must block if able.
1/4

Palm Master #1 - 3GGU
Creature - Treefolk Wizard
When ~ enters the battlefield, place 3 1/2 green plant wizard creature tokens named Grinning Coconut with "Tap: Add one blue or green mana to your mana pool" onto the battlefield.
Tap: Add one green and one blue mana to your mana pool.
2/2

Palm Gaurdian #2 - 3G
Creature - Treefolk
When ~ enters the battlefield, place 3 1/2 green plant wizard creature tokens named Grinning Coconut with "Tap, (G): add one blue mana to your mana pool" and "(U): Add one green mana to your mana pool" to the battlefield.
If a plant token would take damage, the damage is redirected to ~ instead.
~ must block if able.
1/4

Palm Master #2 - 3GGU
Creature - Treefolk Wizard
When ~ enters the battlefield, place 3 1/2 green plant wizard creature tokens named Grinning Coconut with "Tap, (G): Add one blue mana to your mana pool" and "(U): add one green mana to your mana pool" to the battlefield.
Tap: Add one green and one blue mana to your mana pool.
2/2

Palm Master - 2GGU
Creature - Treefolk Wizard (Rare)
When Palm Master enters the battlefield, place 3 blue and green 1/2 plant wizard tokens named Grinning Coconut with "Tap, (G): Add one blue mana to your mana pool" and "(U): add one green mana to your mana pool" to the battlefield.
Tap: Add one green and one blue mana to your mana pool.
2/2

Grinning Coconut - Token

Creature - Plant Wizard
Token (This creature ceases to exist, not even being exiled, when it leaves the battlefield)
Tap, (G): Add one blue mana to your mana pool
(U): add one green mana to your mana pool
1/2