Hi Rosie, collect pine needles twigs and interesting bits and pieces on walks etc. Let them dry out. When using soak in water to make them pliable. It's a bit like coiling aclay our plasticine bowl. You need needle and thread to stitch your coils together. Keep your work flat for a lid. When making the bowl lift your coils up slightly from the previous coil to give a nice bowl shape. Not sure if I've explained well enough but you can look online for more instructions.
Found this you tube, Its very good.  Google makIng a pIne needle basket by TIm Heary. He's good.

Cheers Val