From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A background pattern with a look of rough fabric.
Source V. Hartikainen
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
This is a remix of "flower seamless pattern".I rotated the original image by 90 degrees.This is a seamless pattern of flowers.These horizontal wavy lines are one of Edo patterns which is called "tatewaku or tachiwaku or 立湧" that represents uprising steam or vapor.
Source Yamachem
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
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
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Psychedelic Geometric Background No Black
Source GDJ
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
This one needs to be used in small areas; you can see it repeat.
Source Luca
Prismatic Abstract Line Art Pattern Background
Source GDJ
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin