From an image on opengameart.org shared by rubberduck.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A seamless pattern formed from background pattern 102
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Fix and cc0 to get the tile this is based on.
Source SliverKnight
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
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Prismatic Curved Diamond Pattern No Background
Source GDJ
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
This pattern comes in orange, and it looks as if it is "made of glass".
Source V. Hartikainen