Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A seamless web texture of "green stone".
Source V. Hartikainen
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
Might not be super subtle, but quite original in its form.
Source Alex Smith
This was formed by distorting an image of a background on Pixabay.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Remixed from a drawing that was uploaded to Pixabay by captenpub.
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
A version without colours blended together to give a different look.
Source Firkin
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel