Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
The tile can be had by using shift+alt+i on the selected rectangle in Inkscape
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.
Source V. Hartikainen
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Prismatic Hexagonalist Pattern No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Colourful background achieved with gradient fills.
Source Firkin
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso