There are many varieties of cherries out there and several that will work in pie. Many people opt for tart cherries (Montmorency, Morello, Amarelle, and Early Richmond) so it balances with the added sugar. Other people like to use sweet cherries (Bing, Lapins, Chelan, and Rainier), and some people like a mixture of each. Since you can eat them raw sweet cherries are typically sold in the produce section at the grocery store while tart cherries can be found in the freezer section or at the local farmers market.