A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Someone was asking about how to achieve a fur pattern at #inkscape irc so tried to make a filter on it. Flood filled fractal noises rigged together. May someone find a good use for these.
Source Lazur URH
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
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 No Black
Source GDJ
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso