A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin