A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use 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
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
Abstract Ellipses Background Grayscale
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
It’s big, it’s gradient—and it’s square.
Source Brankic1979
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz