Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Prismatic Curved Diamond Pattern No Background
Source GDJ
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
The tile can be had by using shift+alt+i on the selected rectangle in Inkscape
Source Firkin
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
Prismatic Polyskelion Pattern No Background
Source GDJ
A comeback for you: the popular Escheresque, now in black.
Source Patten
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
Prismatic Hypnotic Pattern No Background
Source GDJ
The image depicts a shell seamless pattern.I used an OCAL clipart called "Shell" uploaded by "jgm104".Thanks.
Source Yamachem
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Spice up your next school project with this icon background.
Source Swetha
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Pattern formed from simple shapes. Black version.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Retro Circles Background 5 No Black
Source GDJ