Retro Squares Background 9 #399
 Dark  CC 0

Retro Squares Background 9

Source GDJ

 More Textures
Nami@2X #576
 Dark  CC BY-SA 3.0

Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!

Source Dertig Media

Light Grey Floral Motif #344
 Wall  CC BY-SA 3.0

Lovely light gray floral motif with some subtle shades.

Source GraphicsWall

Project Papper #119
 Paper  CC BY-SA 3.0

Light square grid pattern, great for a “DIY projects” sort of website, maybe?

Source Rafael Almeida

Black And White Floral Pattern Background Inverse #196
 Dark  CC 0

Black And White Floral Pattern Background Inverse

Source GDJ

Background pattern 19 (black) #203
 Dark  CC 0

A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.

Source Firkin

Concrete Wall #77
 Wall  CC BY-SA 3.0

Dark blue concrete wall with some small dust spots.

Source Atle Mo

Seamless Core Pattern 2 #166
 Dark  CC 0

Seamless Core Pattern 2

Source GDJ

Prismatic Polka Dots 3 No Background #528
 Noise  CC 0

Prismatic Polka Dots 3 No Background

Source GDJ

Medic Packaging Foil@2X #377
 Light  CC BY-SA 3.0

8 by 8 pixels, and just what the title says.

Source pixilated

Little Knobs@2X #311
 Light  CC BY-SA 3.0

White little knobs, coming in at 10x10px. Sweet!

Source Amos

Paper 2 #21
 Paper  CC BY-SA 3.0

New paper pattern with a slightly organic feel to it, using some thin threads.

Source Atle Mo

Polaroid@2X #188
 Wall  CC BY-SA 3.0

Smooth Polaroid pattern with a light blue tint.

Source Daniel Beaton

Background pattern 203 (colour 2) #2485
 Green  CC 0

A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin