A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
More in the paper realm, this time with fibers.
Source Jorge Fuentes
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
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
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
A green background pattern with warped vertical stripes and a grunge look.
Source V. Hartikainen
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
A web texture of brown canvas. Will look great, when used in dark web designs.
Source V. Hartikainen
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
Seamless Olive Green Web Background Image
Source V. Hartikainen
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden