A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
An alternative colour scheme to the original seamless pattern.
Source Firkin
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
This was formed by distorting an image of a background on Pixabay.
Source Firkin