I came across this really cool video on Vimeo about a clay artist, Adam Buick, in Ireland. How he uses the landscape surrounding him and physically going out and collecting his own materials is really awesome.
1:50 in the video is my favorite part. He collects pebbles from a beach nearby and incorporates them into his pots as a glaze and gets a really awesome outcome.
Check it out for yourself, here is the link to the video.
Below is one photo of Buick's pots after using the pebbles he found on the beach to put in his clay.