Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Subtle scratches on a light gray background.
Source Andrey Ovcharov
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin