From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
The classic notebook paper with horizontal stripes.
Source Are Sundnes
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
An alternative colour scheme to the original seamless pattern.
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
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
A nice and simple white rotated tile pattern.
Source Another One
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin