Been living here in Montreal for quite a while now but only just got a concertina at Christmas. I've found there is a musicians session almost every day of the week in Montreal. There is a great tune writer called Jean Duval who's a local here. I'm still trying to get my hands on his book of tunes but if you're into abc here's one called the Halloween Jig.

M:6/8
L:1/8
K:D
F |:B3 Bcd |c2 A ABc |B2 G GAB |A2 F FEF |B3 Bcd |c2 A ABc |def edc |1B3 BAF :|2B3 Bde ::f2 f fed |cde Adc |Bcd dcB |cFF Fde |f2 f fed |cde Adc |Bcd cBA |1B3 Bde :|2B3 B3 :|