Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Alternative colour scheme for the original floral pattern.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A free seamless background with pink spots.
Source V. Hartikainen
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
8 by 8 pixels, and just what the title says.
Source pixilated
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
The image depicts a tiled seamless pattern.The tile represents four leaves aligned every 90 ° , which may look like a bird or a dragon .The original leaf design is from a Japanese old book.
Source Yamachem
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Sharp pixel pattern, just like the good old days.
Source Paridhi
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
This one is amazing, truly original. Go use it!
Source Viahorizon
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios