To get the tile this is formed from 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
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
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
An alternative colour scheme to the original seamless pattern.
Source Firkin
Formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen