A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Colourful background achieved with gradient fills.
Source Firkin
A seamless tessellation pattern. To get the tile this is formed from, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin