I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Derived from a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
A seamless stone-like background for blogs or any other type of websites.
Source V. Hartikainen
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
From a drawing in 'Real Sailor-Songs', John Ashton, 1891.
Source Firkin
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Prismatic Abstract Geometric Background 4
Source GDJ
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
Alternative colour scheme to the original.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso