A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Retro Circles Background 7 No Black
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
A background pattern with wavy green vertical stripes. This one has green stripes on a white background. Download if you like it.
Source V. Hartikainen
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
White circles connecting on a light gray background.
Source Mark Collins
A seamless background pattern of dark brown wood planks.
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
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin