Same classic 45-degree pattern, dark version.
Source Luke McDonald
Original seamless pattern with an Inkscape filter.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Prismatic Groovy Concentric Background 3
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Green Web Background, Seamless tile.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin