Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin