The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
A free seamless background with pink spots.
Source V. Hartikainen
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Prismatic Groovy Concentric Background 2
Source GDJ
Prismatic Abstract Background Design
Source GDJ
Prismatic Groovy Concentric Background
Source GDJ
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
A classic dark tile for a bit of vintage darkness.
Source Listvetra
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ