Hammered Silver Bowls "mid century" from Chaing Ma

My mother is wanting to sell a couple of bowls she got when she lived in Thailand in the late 50s/ early 60s.
They are solid silver and hand hammered. She believes they are from Chiang Mai but it is possible they are from Bangkok. We don’t know where to begin figuring out how much these would be worth.
Any ideas on possible value or where to find some answers?
Thanks![/u]