Green Fibers #91
 Dark  CC BY-SA 3.0

The green fibers pattern will work very well in grayscale as well.

Source Matteo Di Capua

 More Textures
Decorative divider 192 #2503
 Dark  CC 0

From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.

Source Firkin

Polaroid #187
 Wall  CC BY-SA 3.0

Smooth Polaroid pattern with a light blue tint.

Source Daniel Beaton

Background pattern 117 #524
 Noise  CC 0

A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.

Source Firkin

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

Batik Parang Rusak Seamless Pattern(faqeeh)-remix #2450
 Dark  CC 0

As the original image 's page size is too large for its image size, I remixed it.

Source Yamachem

Background pattern 214 #2377
 Blue  CC 0

A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.

Source Firkin

Triangles pattern #2408
 Brown  CC 0

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

Source Firkin

Retro Circles Background 5 #424
 Noise  CC 0

Retro Circles Background 5

Source GDJ

Paven #296
 Grid  CC BY-SA 3.0

A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.

Source Josh Green

Background pattern 19 (outline) #204
 Light  CC 0

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

Source Firkin

Light Aluminum #304
 Wall  CC BY-SA 3.0

Used correctly, this could be nice. Used in a bad way, all hell will break loose.

Source Atle Mo

Beige Paper@2X #84
 Paper  CC BY-SA 3.0

This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.

Source Konstantin Ivanov