Learn 20 shouts

Absorb 20 dragon souls

Returned the Thieves Guild to its former glory

Craft and place a Flower Pot.

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Use Shears to obtain wool from a sheep.

Construct a Dispenser.

Play a music disc in a Jukebox.

Construct one type of each tool (one pickaxe, one spade, one axe and one hoe).

Bake a cake using wheat, sugar, milk and eggs!

Construct a better pickaxe.

Use planks and sticks to make a pickaxe.