A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
Seamless Light Background Texture.
Source V. Hartikainen
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless web texture with illustration of pale color stains on canvas.
Source V. Hartikainen
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
Same classic 45-degree pattern, dark version.
Source Luke McDonald
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
An alternative colour scheme for the original background.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Background formed from the original with an emboss effect.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić