A comeback for you: the popular Escheresque, now in black.
Source Patten
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
A white version of the very popular linen pattern.
Source Ant Ekşiler
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Floral patterns will never go out of style, so enjoy this one.
Source Lasma