Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Abstract Tiled Background Extended 6
Source GDJ
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Continuing the geometric trend, here is one more.
Source Mike Warner
Lovely pattern with some good-looking non-random noise lines.
Source Zucx