A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
This is the remix of "blue wave-seigaiha".The image depicts a seamless pattern of the front upper part of Japanese five yen coin which is used currently.This design represents a rice with ripe golden ears.
Source Yamachem
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Spice up your next school project with this icon background.
Source Swetha
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
8 by 8 pixels, and just what the title says.
Source pixilated
Prismatic Polyskelion Pattern No Background
Source GDJ
Sort of like the Photoshop transparent background, but better!
Source Alex Parker