To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A new one called white wall, not by me this time.
Source Yuji Honzawa
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
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
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Colorful Floral Background No Black
Source GDJ
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin