i would try teach him not to eat pebbles.. cos he can damage his teeth if he tries to chew them. give him something more interesting to do when he does this, otherwise you'll turn it into a game tryin to stop him
if he eats a little pebble he will jsut poo a little pebble. i think as he is such an ickle baby he is still learning max used to do stoopid things like that when he was diddy but he did stop. as for the grass thing max does it every now and again it doesnt seem to make him sick though. as long as its not some exotic plant i wouldnt worry too much