More Textures
Background pattern 215 (colour 4) #2368
 Green  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

Wood Background Pattern #882
 Wood  CC BY-SA 3.0

A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.

Source V. Hartikainen

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

Prismatic Abstract Line Art Pattern Background 2

Source GDJ