They are those vine vegetables that when dry, we buy them to use as bath sponges/exfoliators.
Picture:
http://ny-image0.etsy.com/il_fullxfull.154862984.jpg
I bought a small pack of sliced dried gourds in the 'rodent animal toys' section for $2.99 and my birds LOVE ripping them apart! The texture is slightly rough and the fibers can be broken/shredded pretty easily. Small/medium birds who love shredding, such as budgies, lovebirds, cockatiels, parrotlets would very much enjoy this.