In this page, I will post everything related to background information in the Pikmin series (rests from the human civilization, for example). I will try to classify them (decorations, machines, and so...)

Made by humans

Christmas decorations

These appear in the Fortress of Festivity, in Pikmin 3.

A festive cone. It resembles the Boom Cone from Pikmin 2.
The Boom Cone from Pikmin 2.

A bell. It is similar to the Danger Chime in Pikmin 2.
Danger Chime.png

The Danger Chime from Pikmin 2.

The different baubles which appear in Pikmin 3. A bauble called Essential Furnishing also appears in Pikmin 2.
Essential Furnishing.png

The Essential Furnishing from Pikmin 2.

A red candle. A candle also appears as a treasure in Pikmin 2 : it is called the Fleeting Art Form.
Fleeting Art Form.png

The Fleeting Art Form from Pikmin 2.

A conifer cone in Pikmin 3. It resembles the Conifer Spire from Pikmin 2.
-20Conifer Spire.png

The Conifer Spire from Pikmin 2.

A christmas tree, atop which a star similar to the Innocence Lost can be found.
Innocence Lost.png

The Innocence Lost from Pikmin 2.

A tinsel.
Fairy lights
The different balloons appearing in the Fortress of Festivity.
A snowflake.

Gifts

A gift appears as a collectible treasure in Pikmin 2 : the Joy Receptacle. In Pikmin 3, there are a few gifts that appear in the Fortress of Festivity : they aren't collectible. Here are a few montages showing these gifts :

Joy Receptacle.png

The Joy Receptacle from Pikmin 2.

Stockings

Two stockings appear in the Fortress of Festivity. A stocking called Icon of Progress can also be found in Pikmin 2.

Icon of Progress.png

The Icon of Progress from Pikmin 2.

Tools

A fork and a knife.
A teaspoon.
A spoon in a pot.
A montage showing the different screwdrivers found in Pikmin 3. The green and red screwdrivers can be found in Clockwork Chasm, while the blue and yellow screwdrivers can be found in the Corroded Maze.
A pair of diving goggles.
A snorkel.
The different buckets appearing in Pikmin 3.
An orange sieve in the Forgotten Cove.
A blue sieve in the Forgotten Cove.
A shovel in the Forgotten Cove.
A rake in the Forgotten Cove.

Gutters

Gutters can be found in Pikmin 2 and Pikmin 3.

A gutter in The Rustyard.
A gutter in the Shower Room.

Light bulbs

In Pikmin 2, there's a collectible light bulb called the Stellar Orb. In Pikmin 3, they are used to light caves.

The Stellar Orb from Pikmin 2.
Light bulbs.png

A light bulb in Pikmin 3.

Tiles and fabric

The two different tiles appearing in the Fortress of Festivity.
The tiles that can be found in the Shower Room.
Fabric.png

Some fabric that can be found in the Glutton's Kitchen.

Bolts

Bolts are found in Pikmin, Pikmin 2 and Pikmin 3.

The Extraordinary Bolt from Pikmin.
-96Superstrong Stabilizer.png

The Superstrong Stabilizer from Pikmin 2.
Two bolts in Pikmin 3. They're quite similar to the Extraordinary Bolt.
-97Repair Juggernaut.png

The Repair Juggernaut from Pikmin 2.

Plates

Plates appear in Pikmin 2. They appear in the Glutton's Kitchen.

A yellow plate with frogs.
A blue plate.
A yellow plate.
A pink plate.

Unclassified

A glove which resembles the Five-man Napsack.
The Five-man Napsack from Pikmin 2.

A tyre. Tyres appear in Pikmin 3 and are found in the following areas : Stagnant Sea, Sandpit Kingdom.
A ball.
A montage showing the control valves appearing in Pikmin 3. The white valve appears in the Corroded Maze, whereas the others appear in the Clockwork Chasm.
The two different tiles appearing in the Fortress of Festivity.
A traffic cone.
A wall made of bricks in the Garden of Hope.
A padlock in The Rustyard.
A pizza in the Fortress of Festivity.
The cardboard box used for the pizza. The pattern is actually the Italian flag.
A basket in the Fortress of Festivity.