A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Seamless Prismatic Geometric Pattern With Background
Source GDJ
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Prismatic Hexagonalism Pattern No Background
Source GDJ
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning