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
Abstract Tiled Background Extended 12
Source GDJ
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Black brick wall pattern. Brick your site up!
Source Alex Parker
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
Abstract Tiled Background Extended 10
Source GDJ
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin