Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
A pattern derived from part of a fractal rendering in Paint.net.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
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
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
Prismatic Hypnotic Pattern No Background
Source GDJ
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin