A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
f you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
You know you love wood patterns, so here’s one more.
Source Richard Tabor
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
Might not be super subtle, but quite original in its form.
Source Alex Smith
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen