This background has abstract texture with some similarities to wood.
Source V. Hartikainen
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Inspired by an image that was uploaded to Pixabay by geralt
Source Firkin
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Looks like an old wall. I guess that’s it then?
Source Viahorizon
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin