Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Pattern produced in Paint.net using the Vibrato plug-in.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Here's a new background image for websites with a seamless pink texture. It should look beautiful with website themes where light pink background is needed. The background is seamless, therefore it should be used as a tiled background.
Source V. Hartikainen
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
Prismatic Polka Dots 3 No Background
Source GDJ
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic