A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
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
A seamless texture of worn out "cardboard".
Source V. Hartikainen
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns