To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
From an image on opengameart.org shared by rubberduck.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
An abstract pale yellow paper-like background with stains colored in yellow and green.
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
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Abstract Tiled Background Extended 8
Source GDJ
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
8 by 8 pixels, and just what the title says.
Source pixilated