I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen
Retro Circles Background 5 No Black
Source GDJ
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
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
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The image depicts a shell seamless pattern.I used an OCAL clipart called "Shell" uploaded by "jgm104".Thanks.
Source Yamachem
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen