This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Black brick wall pattern. Brick your site up!
Source Alex Parker
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
This is a seamless pattern of a woody texture.The original image is here:https://pixabay.com/ja/users/ClassicallyPrinted-1302233/
Source Yamachem
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez