There are two collections that I would recommend.
Singers and Songs of Canada, a 3 CD set on the Mercury label, compiled by Smithsonian-Folkways in 1996.
Canadian Folk Songs, A Centennial Collection. This is a nine-album long play record collection produced by the CBC in collaboration with RCA Victor.
I'm not sure if either of these collections meets your definition of 'field recordings', but they are the definitive collections at the moment.
Also explore the growing collection of sound recordings available on the Virtual Gramophone site at the National Library... http://www2.nlc-bnc.ca/gramophone/.
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