A free pink background pattern.
Source V. Hartikainen
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
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
Black And White Floral Pattern Background Inverse
Source GDJ
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Prismatic Geometric Pattern Background
Source GDJ
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
It looks very nice I think.
Source V. Hartikainen
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn