Rachel and Nick Cope, the 30-something couple behind Calico Wallpaper, had wanted to make textile versions of their mural-style wallpapers since they founded their company in 2013. Now, fans of Calico can finally decorate their pillows and windows in Rachel’s ‘‘asymmetrical, organic’’ patterns — which she prints and paints in her studio before they’re transferred digitally — with fabrics from their sister line, Cope.