The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
Zero CC tillable hard cover red book with X shape marks. Scanned and made by me.
Source Sojan Janso
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 Hypnotic Pattern No Background
Source GDJ
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
The image depicts a pattern of regular hexagon.As I made to use it for myself,I want to others to use it.Speaking about the ratio of the image, height : width = 2 : √3(1.732...)Ridiculous to say,I realized later that this image is not honey comb pattern.I have to slide the second row.
Source Yamachem
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
Prismatic Curved Diamond Pattern No Background
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin