Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless Green Tile Background
Source V. Hartikainen
Prismatic Groovy Concentric Background 5
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
A background pattern with wavy green vertical stripes. This one has green stripes on a white background. Download if you like it.
Source V. Hartikainen
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin