There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
This is the remix of "Tileable Wave Pattern 2" uploaded by "Arvin61r58".Thanks.I added a wire-mesh fence seamless pattern as a lower layer.
Source Yamachem
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Alternative colour scheme to the original.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić