Background pattern 258 (colour) #2134
 Red  CC 0

Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

 More Textures
Inflicted #117
 Grid  CC BY-SA 3.0

Dark squares with some virus-looking dots in the grid.

Source Hugo Loning

Background pattern 252 (colour 3) #2160
 Green  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

Diamond pattern (colour 8) #2273
 Red  CC 0

From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Micro Carbon #7
 Carbon  CC BY-SA 3.0

Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.

Source Atle Mo

Decorative divider 254 #2040
 Dark  CC 0

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

Source Firkin

Background pattern 314 #1839
 Yellow  CC 0

The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

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

Dark Denim@2X #373
 Dark  CC BY-SA 3.0

Thin lines, noise and texture creates this crisp dark denim pattern.

Source Marco Slooten

Batthern #324
 Grid  CC BY-SA 3.0

Sometimes simple really is what you need, and this could fit you well.

Source Factorio.us Collective

Sports car pattern #2442
 Red  CC 0

A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Background pattern 253 #2153
 Brown  CC 0

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

Source Firkin

Retro Circles Background 6 #428
 Noise  CC 0

Retro Circles Background 6

Source GDJ

Inflicted@2X #118
 Grid  CC BY-SA 3.0

Dark squares with some virus-looking dots in the grid.

Source Hugo Loning