A bit of scratched up grayness. Always good.
Source Dmitry
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Prismatic Abstract Line Art Pattern Background
Source GDJ
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
If you need a green background for your blog/website, try this one. Remember that Green Striped Background is seamlessly tileable.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
A nice and simple white rotated tile pattern.
Source Another One