Has anyone seen the Kham Mueang Dictionary พจนานุกรมคำเมือง in Chiang Mai? Heard about it but didn't see it at Surawong.

I would imagine that Surawong has at least one, but it might be hard to find without asking the staff (if you're not confident speaking, just write down what you're looking for on a piece of paper and show it to them).

Otherwise, try Duangkamol. They've got lots of dictionaries (and probably a Thai-Lanna one) downstairs, and if you go upstairs and turn right, you'll bump right into a shelf full of books on the Lanna and Tai-Yai/Shan languages (teach yourself-type books, not linguistics theses, but written for Thais of course) as well as the Thai Tham script used to write them. Whether they stock dictionaries on the same shelf or not I didn't notice the last time I was there, but if not they'll be downstairs in the dictionary section. Bring a piece of paper with พจนานุกรมคำเมือง written on it as a last resort, and you'll go home happy.