Dishes, cups, bottles to snmash, glass globs/nuggets, pebbles....bottle caps, ball chain...

Yes-interesting small figurines like salt and peppers, pretty plates ceramic tiles, pretty old jewelry thats too awful to wear makes wonderful mosaic material! basically anything thats small and pretty. old shower hooks with figures, shells. Things to mosaic ON might include picture frames, orbs, simple ceramic figurines-simple shapes without a lot of texture to them, plaques or wood slabs, candle holders.
Basically if it is blingy and colorful and you can break it or glue it to something its fair game! And the unusual is always a prize.