the bolivian locals chew mouthfuls of coca leaves to prevent altitude sickness; some parts of bolivia are very high up. other put them in tea to make coca tea. they also use them to make offerings to the holy gods in return for protection from evil spirits and good luck. you can buy bags of dried leaves, which call for an interesting present.
in the potosi silver mines, bolivian miners traditionally drink 96% proof alcohol, which you can try (and buy) on a tour of the silver mines.
there are loads of companies who run death road tours out of la paz. for those who successfully make it to the bottom of death road (locally known as yungas road) a souvenir t-shirt is offered to remember the occasion.
in the potosi silver mines, bolivian miners still use dynamite to expand tunnels and clear heavy rock debris. the miners tend to work extremely long +12 hour shifts, some of them beginning at 2am.
the salar de uyuni is a focal point and destination for many travellers visiting bolivia, and it's possible to buy a pack of salt as excavated and exported from the bolivian salt flats.