It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
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 with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A repeating graphic with ancient pattern. I came up with this name/title at last minute, so you may find that there is very little of ancientness in this pattern after all.
Source V. Hartikainen
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin