A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Prismatic Polka Dots Mark II No Background
Source GDJ
Background pattern originally a PNG drawn in Paint.net
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
Background formed from the original with an emboss effect
Source GDJ
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
Almost like little fish shells, or dragon skin.
Source Graphiste
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-brown.
Source Yamachem
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A free seamless background pattern for use on websites.
Source V. Hartikainen
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac