A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. A version of the original with random colors.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A bit strange this one, but nice at the same time.
Source Diogo Silva
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley