A seamless background texture of old cardboard.
Source V. Hartikainen
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
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
A seamless texture of black leather. I think it will look best when used in headers, footers or sidebars.
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Plywood Web Background background image for use in web design.
Source V. Hartikainen
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin