It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ
Feel free to download this "Dark Wood" background texture for your web site. The background tiles seamlessly!
Source V. Hartikainen
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin