CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
Used the 6th circle pattern designed by Viscious-Speed to create a print that can be used for card making or scrapbooking. Save as a PDF file for the best printing option.
Source Lovinglf
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
A pale olive green background with a seamless texture.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
A brown metallic grid pattern layered on top of a dark fabric texture. It should look great when using as a tiled background on web pages, especially blogs.
Source V. Hartikainen
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
The rectangular tile this is based on 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
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Sort of like the Photoshop transparent background, but better!
Source Alex Parker