Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
So tiny, just 7 by 7 pixels – but still so sexy. Ah yes.
Source Dmitriy Prodchenko
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
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
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Sort of reminds me of those old house wallpapers.
Source Tish
Colorful Floral Background No Black
Source GDJ
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
A version without colours blended together to give a different look.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett