An attempt for cleaning up the original image in a few steps.
Source Lazur URH
Prismatic Groovy Concentric Background
Source GDJ
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
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
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Embossed lines and squares with subtle highlights.
Source Alex Parker
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
Abstract Tiled Background Extended 8
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay