From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
8 by 8 pixels, and just what the title says.
Source pixilated
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Colorful Floral Background 3 No Black
Source GDJ
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The image is a seamless pattern of a fishnet.
Source Yamachem
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Prismatic 3D Isometric Tessellation Pattern 6
Source GDJ
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
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
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous