Tiles, stones, pebbles and sea shells please- for school project! (Saltdean BN2)

Dear Freeglers. My Yr 3 class are making a large mosaic to be entered into an art exhibition in Seaford. We would be very grateful for any plain-coloured tiles of any shape/size, stones, pebbles and seashells to help us on our way to creating something beautiful. Thanks in advance for reading this.