Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Pattern produced in Paint.net using the Vibrato plug-in.
Source Firkin
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
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
A seamless background of warped stripes on paper.
Source V. Hartikainen
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Prismatic Groovy Concentric Background 2
Source GDJ
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.
Source BAJ
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin