To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A seamless paper background colored in pale yellow.
Source V. Hartikainen
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Original minus the background
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
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
Seamless Green Tile Background
Source V. Hartikainen