A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless background of warped stripes on paper.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Colorful Floral Background 3 No Black
Source GDJ
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
A black tile-able background with paper-like texture.
Source V. Hartikainen
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Classic vertical lines, in all its subtlety.
Source Cody L
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein