A quick thing to look out for in Thailand, roasting chestnuts, the black beads are special sand they are roasted in so they cook evenly and all the way through. Chestnut season is late summer, through to autumn, and the smell of freshly roasted chestnuts is delightful. If you're visiting at this time you'll see quite a few of these, especially in Chinese areas.

These I saw in China town, a packet of fresh roasted chestnuts was 20 Baht.