A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Remixed from a design seen on Pixabay. The basic tile 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
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
There are many carbon patterns, but this one is tiny.
Source Designova
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
It looks very nice I think.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
A nice one indeed, but I have a feeling we have it already? If you spot a copy, let me know on Twitter.
Source Graphiste
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen