A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
The name is totally random, but hey, it sounds good.
Source Atle Mo
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Embossed lines and squares with subtle highlights.
Source Alex Parker
Subtle scratches on a light gray background.
Source Andrey Ovcharov
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin