Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Sometimes you just need the simplest thing.
Source Fabricio
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
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
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez