Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
A seamless texture of a rough concrete surface.
Source V. Hartikainen
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
White handmade paper pattern with small bumps.
Source Marquis
A background pattern with green vertical stripes. A new striped background pattern. This time a green one.
Source V. Hartikainen
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić