A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
Similar to original, but without gaps in between the arrows. This seamless pattern was created from a rectangular tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne