Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
White circles connecting on a light gray background.
Source Mark Collins
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
A pale olive green background with a seamless texture.
Source V. Hartikainen
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin