This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
Prismatic Groovy Concentric Background 4
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Light and tiny, just the way you like it.
Source Rohit Arun Rao
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
All good things come in threes, so I give you the third in my little concrete wall series.
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
Seamless Green Tile Background
Source V. Hartikainen
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo