Strawbs "From the Witchwood" and "Grave New World". There are a few songs on each that are too heavy to be pastoral, but the overall effect is there. Probably their early album "Dragonfly" is closes to being pastoral all the way through.
Certainly Amazing Blondel, all the albums up to and including "Blondel", and even, to a lesser extent, "Mulgrave Street" and "Inspiration"
Clannad is Irish but often very pastoral, especially "Clannad 2", Dulaman" and "Fuaim"
Paul Brett's "Songs from the Compleat Angler"
Fuchsia, both their first self titled and their recent comeback
Another Irish group "Loudest Whisper"
Madden and Harris "Fool's Paradise"
Tir Na Nog (also Irish), "A Tear and a Smile"
A few other obscure ones come to mind, like O.W.L (Of Wondrous Legends)