Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Prismatic Abstract Geometric Background 2
Source GDJ
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Prismatic Hexagonalist Pattern No Background
Source GDJ
You guessed it – looks a bit like cloth.
Source Peax Webdesign
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
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
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Prismatic Geometric Pattern Background No Black
Source GDJ