A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Prismatic Polka Dots 3 No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
The classic notebook paper with horizontal stripes.
Source Are Sundnes
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Retro Circles Background 7 No Black
Source GDJ
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Sharp pixel pattern, just like the good old days.
Source Paridhi
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Sort of reminds me of those old house wallpapers.
Source Tish
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
Colourful background achieved with gradient fills.
Source Firkin
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin