This is sort of fresh, but still feels a bit old school.
Source Martuchox
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Pattern formed from simple shapes. Black version.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin