Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
This one is amazing, truly original. Go use it!
Source Viahorizon
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin