Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless tessellation pattern. To get the tile this is formed from, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
Inspired by a pattern found in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle 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
Background formed from the original with an emboss effect
Source GDJ
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen