From an image on opengameart.org shared by rubberduck.
Source Firkin
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Prismatic Polka Dots 3 No Background
Source GDJ
Looks like an old wall. I guess that’s it then?
Source Viahorizon
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Background pattern originally a PNG drawn in Paint.net
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
The image depicts a shell seamless pattern.I used an OCAL clipart called "Shell" uploaded by "jgm104".Thanks.
Source Yamachem
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Prismatic Polka Dots 3 No Background
Source GDJ
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
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH