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
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Classic vertical lines, in all its subtlety.
Source Cody L
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ