I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Abstract Ellipses Background Grayscale
Source GDJ
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A comeback for you: the popular Escheresque, now in black.
Source Patten
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Utilising some flowers from Almeidah. To get the unit 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
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman