Cardboard@2X #279
 Paper  CC BY-SA 3.0

A good starting point for a cardboard pattern. This would work well in a variety of colors.

Source Atle Mo

 More Textures
Candyhole #356
 Light  CC BY-SA 3.0

It’s a hole, in a pattern. On your website. Dig it!

Source Josh Green

Prismatic Octagonal Background #439
 Noise  CC 0

Prismatic Octagonal Background

Source GDJ

Colorful Floral Background 2 #487
 Dark  CC 0

Colorful Floral Background 2

Source GDJ

Black And White Floral Pattern Background Inverse #197
 Dark  CC 0

Black And White Floral Pattern Background from PDP.

Source GDJ

Background pattern 270 #2061
 Dark  CC 0

A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Background pattern 252 (colour) #2161
 Colorful  CC 0

Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Prismatic Groovy Concentric Background No Black #451
 Noise  CC 0

Prismatic Groovy Concentric Background No Black

Source GDJ

Heart and rose pattern #2419
 Pink  CC 0

Seamless pattern formed from a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.

Source Firkin

Diagonal Noise #181
 Fabric  CC BY-SA 3.0

A simple but elegant classic. Every collection needs one of these.

Source Christopher Burton

Dark Wood@2X #321
 Wood  CC BY-SA 3.0

A beautiful dark wood pattern, superbly tiled.

Source Omar Alvarado

Transparent Square Tiles@2X #299
 Grid  CC BY-SA 3.0

The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.

Source Nathan Spady

Retro Circles Background 4 No Black@2X #423
 Dark  CC 0

Retro Circles Background 4 No Black

Source GDJ

Background pattern 308 (colour 5) #1869
 Blue  CC 0

Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.

Source Firkin

Axiom Pattern #330
 Grid  CC BY-SA 3.0

Not even 1kb, but very stylish. Gray thin lines.

Source Struck Axiom

Background pattern 302 (colour 2) #1893
 Dark  CC 0

The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.

Source Firkin