You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
A bit of scratched up grayness. Always good.
Source Dmitry
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
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 drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
A comeback for you: the popular Escheresque, now in black.
Source Patten
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo