More Textures
Background pattern 306 (colour 3) #1880
 Colorful  CC 0

Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.

Source Firkin

45-Degree Fabric@2X #2
 Fabric  CC BY-SA 3.0

Medium gray fabric pattern with 45-degree lines going across.

Source Atle Mo

MBossed@2X #194
 Grid  CC BY-SA 3.0

Embossed lines and squares with subtle highlights.

Source Alex Parker

Desert Camo Print #255
 Fabric  CC 0

Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.

Source Eady

Background pattern brown #1951
 Brown  CC 0

To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Decorative divider 254 #2040
 Dark  CC 0

Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857

Source Firkin

Diamonds Are Forever #183
 Diamond  CC BY-SA 3.0

Sharp diamond pattern. A small 24x18px tile.

Source Tom Neal

Prismatic Geometric Pattern Variation 2 With Background@2X #472
 Noise  CC 0

Prismatic Geometric Pattern Variation 2 With Background

Source GDJ

Checkered Light Emboss #280
 Grid  CC BY-SA 3.0

Sort of like the Photoshop transparent background, but better!

Source Alex Parker

"Dark Metal Plate", Web Background #1084
 Metal  CC BY-SA 3.0

A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.

Source V. Hartikainen