A seamless texture of a rough concrete surface.
Source V. Hartikainen
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
f you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Abstract Tiled Background Extended 12
Source GDJ
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Prismatic Polka Dots 3 No Background
Source GDJ