Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Run a restaurant blog? Here you go. Done.
Source Andrijana Jarnjak
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Black And White Floral Pattern Background from PDP.
Source GDJ
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin