This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
This is a hot one. Small, sharp and unique.
Source GraphicsWall
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Oh yes, it happened! A pattern in full color.
Source Atle Mo
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Prismatic Abstract Background Design
Source GDJ
Prismatic Hexagonalist Pattern No Background
Source GDJ