More Textures
Prismatic Abstract Line Art Pattern Background 2 #567
 Dark  CC 0

Prismatic Abstract Line Art Pattern Background 2

Source GDJ

Background pattern 314 (colour 5) #1835
 Pink  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

MBossed@2X #194
 Grid  CC BY-SA 3.0

Embossed lines and squares with subtle highlights.

Source Alex Parker

Seamless tile 4 #1812
 Red  CC 0

Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern

Source Firkin

Prismatic Curved Diamond Pattern 2 No Background@2X #539
 Diamond  CC 0

Prismatic Curved Diamond Pattern 2 No Background

Source GDJ

Vichy #71
 Light  CC BY-SA 3.0

This one could be the shirt of a golf player. Angled lines in different thicknesses.

Source Olivier Pineda

Candyhole #356
 Light  CC BY-SA 3.0

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

Source Josh Green

Leafy design 18 (colour)@2XaFloral design 96 (colour) #1787
 Green  CC 0

From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.

Source Firkin

Seamless Core Pattern 10 #171
 Dark  CC 0

Seamless Core Pattern 10

Source GDJ

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