Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
The name is totally random, but hey, it sounds good.
Source Atle Mo
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten