I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
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
Tiny circle waves, almost like the ocean.
Source Sagive
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ