Frank was interested in prunes. He would eat the prunes my mother offered him (she had digestive problems like his). He would eat our prune kolacki. Later c. 1962 (summer), I tried to introduce him to a Scrippsie I met while she and I were working at the Shakespeare Festival in town because she was a prune heiress and had a good sense of humor and had heard of the Grapes of Wrath. She pointed out that the people who came to work her dad's ranch lived in shacks and other dire circumstances, "Like something out of the Grapes of Wrath" she ... exclaimed her punch line with a bit of a laugh.
Frank and everyone else of the time enjoyed this prune commercial (1960):