An attempt for cleaning up the original image in a few steps.
Source Lazur URH
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
A repeating background with wood/straw like texture.
Source V. Hartikainen
From a drawing in 'Less Black than we're painted', James Payn, 1884.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Prismatic Floral Background No Black
Source GDJ
Retro Circles Background 7 No Black
Source GDJ
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
Colour version of the original seamless pattern.
Source Firkin
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