Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!
Source Firkin
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
A seamless pattern formed from a rectangular tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
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
Colorful Floral Background No Black
Source GDJ
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Looks like an old rug or a computer chip.
Source Patutin Sergey
A seamless pattern formed from background pattern 102
Source Firkin