A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
The image depicts a tiled seamless pattern.The tile represents four leaves aligned every 90 ° , which may look like a bird or a dragon .The original leaf design is from a Japanese old book.
Source Yamachem
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
The perfect pattern for all your blogs about type, or type-related matters.
Source Atle Mo
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Prismatic Hexagonalist Pattern No Background
Source GDJ
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
An alternative colour scheme for the original background.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin