I found together a total of eleven of these rppcs documenting the growth of beans, corn, peas and oats in various soils and combinations, and just love them--as beautiful photographs, for their indexical nature, for the wonderful hand-written labels on the planters, and for being, as far as I know, quite unusual. The fact that they were produced as postcards suggests they were made to be sent, but the backs are all blank, so perhaps they just served as reference for the grower, who I like to picture carrying them all in to Modern Photo Studio in downtown Boston, c.1910s-20s, and setting them proudly before H.A. Kazanjian to photograph.
I have divided them into groups based on character of photos, and plants! Two of these are beans growing in different mixes, the center one with corn added. All measure 3 1/2" x 5 1/2" and are in very good condition.