By the way what a potato car? Plus does anyone have any photos of WW&F milk and potato cars? I would like to see them!

According to the book I have, Two Feet to Tidewater, there were 10 Potato Cars, numbered 501 to 510. They were rebuilt from W&Q Flat cars (originally built by Portland in 1894) into potato cars in 1910-1911. Basically a box car with a stove in them to provide heat to keep the potatoes from freezing.
I do not have any pictures of them to post, but the books I have on the WW&F show the potato cars as a box car with a smoke stack on top.
As for the Turner Dairy Centre milk cars, I found a picture of Milk car #65 in the book, Two Feet to Tidewater, and it too has a smoke stack on the roof. I am guessing to keep the milk from freezing in the winter. The book says #65 was an insulated milk reefer, lettered for Turner Centre Dairy Assoc., built in 1906 by Portland.
Ah! I just found a drawing of Milk Car #65 in the book Two Feet to Tidewater, and it mentions that #65 was in service as a potato car in later years. According to the comments in the book, it was originally boxcar red with white lettering, then re-painted reefer yellow, with a green roof without lettering or numbers for potato service. And automatic couplers were added in approx. 1916.
No, I did not spell it incorrectly. The book spells it Centre.