A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Dark blue concrete wall with some small dust spots.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
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
The image depicts polka dot seamless pattern.
Source Yamachem
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
A comeback for you: the popular Escheresque, now in black.
Source Patten
The perfect pattern for all your blogs about type, or type-related matters.
Source Atle Mo
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
A free seamless background pattern for use on websites.
Source V. Hartikainen
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile