Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Embossed lines and squares with subtle highlights.
Source Alex Parker
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić