Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
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
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Prepared mostly as a raster in Paint.net and vectorised.
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
CC0 and seamless wellington boot pattern.
Source SliverKnight
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
From a drawing in 'A Rolling Stone. A tale of wrongs and revenge', John Hartley, 1878.
Source Firkin
I’m not going to use the word Retina for all the new patterns, but it just felt right for this one. Huge wood pattern for ya’ll.
Source Atle Mo
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio