If anyone is interested in this kind of etymology, academic Kenneth Henshall has written 'A Guide To Remembering Japanese Characters' which contains the etymologies for the ~2000 general use Kanji. Over the millennia of evolution of the characters, some characters have multiple disputed etymologies which are still unresolved by the academics who study the history.

For the record, 食 is a pictogram of a small amount of food (the "roof" looking thing) stacked on a heavily stylized pictogram of a kind of table or plate (do an image search for 'takatsuki table'). It's claimed the Japanese word for bean 豆, has an older stylization of the same takatsuki table with a little bit of food at the top.

From a learning to read and memorization perspective, most people will probably find doing Look/Cover/Write/Check type drills (either manually or with a spaced repetition flashcard program like Anki) much more effective than using mnemonics based on (sometimes very complex) etymology.