Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Element of beach pattern with background.
Source Rones
A free pink background pattern.
Source V. Hartikainen
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Sort of reminds me of those old house wallpapers.
Source Tish
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
Zero CC tillable hard cover red book with X shape marks. Scanned and made by me.
Source Sojan Janso
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Zero CC tileable moss or lichen covered stone texture, edited from pixabay. CC0
Source Sojan Janso
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin