Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Geometric triangles seem to be quite hot these days.
Source Pixeden
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
An alternative colour scheme for the original seamless texture formed from an image on Pixabay.
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Colourful background achieved with gradient fills.
Source Firkin
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
8 by 8 pixels, and just what the title says.
Source pixilated
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers