Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ