A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
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
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A free pink background pattern.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin