Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
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
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
The original enhanced with one of Inkscapes's filters.
Source Firkin
Original seamless pattern with an Inkscape filter.
Source Firkin