This was formed by distorting an image of a background on Pixabay.
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
Dark blue concrete wall with some small dust spots.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
A seamless background texture of old cardboard.
Source V. Hartikainen
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Geometric triangles seem to be quite hot these days.
Source Pixeden
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Background formed from the original with an emboss effect
Source GDJ
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH