A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Seamless Light Background Texture.
Source V. Hartikainen
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
8 by 8 pixels, and just what the title says.
Source pixilated
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin