This appears to be vol 39 and "Bushels of Bread Corn" vol 40, but what was the series called? and is their a list of the volume titles?

Paths of Peace v59 1938 & Bushels of Bread Corn v60 1939, are both volumes of The Believer's Pathway. Plenteous Redemption v60 1938, Ed. by Hy. Pickering, is a volume of "The Herald of Salvation" Alex. Marshall also edited a Herald volume, v35 1913 with the same title.
The Believer's Pathway began with v1 1880.
The Herald of Salvation began with v1 1879.
They both have the same codes, which can be somewhat confusing.
The Herald has a "H" before the vol. # on some volumes.
The Pathway has a "P" before the vol # on some volumes.