Micro Carbon@2X #8
 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

 More Textures
Background pattern 66 #195
 Wall  CC 0

A background pattern drawn in Inkscape.

Source Firkin

Diamond pattern (colour 2) #2284
 Green  CC 0

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

Source Firkin

Tessellation 15 (colour 2) #2221
 Yellow  CC 0

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

Source Firkin

Prismatic Abstract Geometric Background 4 #271
 Noise  CC 0

Prismatic Abstract Geometric Background 4

Source GDJ

Background pattern black #2028
 Dark  CC 0

Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

crissXcross@2X #112
 Dark  CC BY-SA 3.0

Dark pattern with some nice diagonal stitched lines crossing over.

Source Ashton

Fabric pattern (colour 3) #2400
 Fabric  CC 0

Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Seamless Core Pattern 5 #169
 Dark  CC 0

Seamless Core Pattern 5

Source GDJ

Graphene pattern 2 #2234
 Dark  CC 0

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

Source Firkin

Triangles@2X #128
 Dark  CC BY-SA 3.0

Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.

Source Ivan Ginev

Retro Circles Background 8 No Black@2X #438
 Dark  CC 0

Retro Circles Background 8 No Black

Source GDJ