Light and tiny, just the way you like it.
Source Rohit Arun Rao
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
A criss-cross pattern similar to one I saw mown into a sports field.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
This one is amazing, truly original. Go use it!
Source Viahorizon
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Prismatic Abstract Background Design No Black
Source GDJ
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Number five from the same submitter, makes my job easy.
Source Dima Shiper
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
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
Prismatic Abstract Geometric Background 5
Source GDJ
Prismatic Groovy Concentric Background
Source GDJ
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ