A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
A background pattern with a look of rough fabric.
Source V. Hartikainen
A seamless pattern formed from background pattern 102
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
8 by 8 pixels, and just what the title says.
Source pixilated
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
This is the remix of "blue wave-seigaiha".This is the flowers of pink silk tree which is called "nemuno-ki".About pink silk tree ,refer to here:https://jp.pinterest.com/pin/500744052301210439/
Source Yamachem
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Prismatic Polyskelion Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso