Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Prismatic Groovy Concentric Background 2
Source GDJ
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
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
Prismatic Abstract Background Design
Source GDJ
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
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen