This was formed by distorting an image of a background on Pixabay.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Geometric triangles seem to be quite hot these days.
Source Pixeden
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
A repeating background of beige paper with vintage look. Repeats to infinity, as usual.
Source V. Hartikainen
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin