The original enhanced with one of Inkscapes's filters.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
Tiny circle waves, almost like the ocean.
Source Sagive
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
Seamless SVG vector and JPG backgrounds with faded diagonal stripes. The colors are editable.
Source V. Hartikainen
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
Feel free to download this "Dark Wood" background texture for your web site. The background tiles seamlessly!
Source V. Hartikainen
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
Sort of reminds me of those old house wallpapers.
Source Tish
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin