Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
A pale olive green background with a seamless texture.
Source V. Hartikainen
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso
Subtle scratches on a light gray background.
Source Andrey Ovcharov
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Background formed from the original with an emboss effect.
Source Firkin
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav