@donasmrs-- As far as I know, Morello is an American type of sour cherry, so it definitely grows in the US. My sister has a Morello cherry tree and she lives in Texas. I think that's USDA zone 8.
I can't get them fresh where I am either and I also buy mine jarred from the organic market. I highly recommend using Morello cherries in chocolate cake, like black forest cake. Morello cherries and chocolate are perfect together. In the summer, I also use this cherry as a topping on ice cream.
I want to experiment more with these cherries though. I want to make a sauce out of it for meat. The liquor sounds very tempting too, but I will need some help for that.