A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
White little knobs, coming in at 10x10px. Sweet!
Source Amos
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Zero CC plastic pattern texture, photographed and made by me. CC0 *Note, this texture was on the perfectly smooth surface of a plastic shovel scraper, not sure how to call it. Plz coment if you know what its called.
Source Sojan Janso
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
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 seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
Prismatic Snowflakes Pattern 2 No Background
Source GDJ