CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
A seamless textured paper for backgrounds. Colored in pale orange hues.
Source V. Hartikainen
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
Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo