A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
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
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Alternative colour scheme for the original floral pattern.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
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
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Here's a new background image for websites with a seamless pink texture. It should look beautiful with website themes where light pink background is needed. The background is seamless, therefore it should be used as a tiled background.
Source V. Hartikainen
Prismatic Curved Diamond Pattern No Background
Source GDJ
White circles connecting on a light gray background.
Source Mark Collins
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo