CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Someone was asking about how to achieve a fur pattern at #inkscape irc so tried to make a filter on it. Flood filled fractal noises rigged together. May someone find a good use for these.
Source Lazur URH
Alternative colour scheme for the original floral pattern.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Seamless Prismatic Geometric Pattern With Background
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib