Food for Thought...(note the meta-metaphor title) 8]

Finding food metaphors in my life by myself was a LOT harder than it was in class!
Here's what I found:

1.From the expressions:
"Peachy-keen!"
"As easy as apple pie"
"It was a piece of cake"
"Sweet!"
"Fruitful efforts"

I propose the connection: "Good Fortune is Sweet Food"

Here, I use this particular definition of "fortune," entry 3 from the OED:

A Hogwarts cake like this DESERVES celebration!
Credit: here

The chance or luck (good or bad) which falls to any one as his lot in life or in a particular affair. 

Analysis:
If someone were to undertake a difficult endeavor, such as taking a midterm (#ughthisweek!), and found that the exam was actually doable-easy, they might say "Oh, this was a piece of cake," or "it was as easy as apple pie!" Similarly, the slang expressions "peachy keen" and the modern equivalent "sweet!" are defined as "excellent, wonderful" and are used when some good situation occurs, such as getting a good grade, having a positive encounter with the (opposite) desired gender, inheriting a beach house, etc. "Fruitful efforts" refers to having good results with your endeavors, and I associate this partially with the concept of "fortune," because we all know life is unfair, and you don't always get what you deserve, even if you put a lot of work in!

Using sweet foods to express good fortune has logical connections: the taste of sweet was known to early humans as a good source of calories (berries, fruits), as opposed to salty (questionable food source?), sour (unnripe food source?), and bitter (potentially deadly food source). Children prefer sweet foods, and many people have "sweet tooths," so liking the taste of sweet has  been with us since infancy and is therefore, familiar and comfortable. Association of "sweet = calorie-rich" and "sweet = good" is related to other cultural aspects:
-"You're so sweet!/That's so sweet of you!" Sweet as a positive trait.
-Cute names like "cupcake" and "sweetie pie," never mind the sexist overtones...
-Sweets as treats and desserts.

Desserts particularly are of interest. I am reading a book about the history of dessert. For now though, desserts are enjoyed at the end of a meal, treats to be savored and appreciated, both in terms of taste and looks, and sometimes indicative of class or social status. Desserts are not necessary to the meal, but are often used to celebrate occasions (ie; a birthday cake), so this may be a reason why sweets are associated with positive occurrences in life.


2. From the expressions:

Eating crow!
Credit: here

"Eat your words"
"Have a taste of your own medicine"
"Bitter pill to swallow"
"Eat crow"
* "Eat humble pie"

I propose the connection: "Unpleasant, Deserved Life Experiences are Bitter Foods."

Obviously here I am connecting food and medicine as one, but think about the time when medicine was limited to certain foods, herbs, plants, etc. "To eat your words" is to concede that you were wrong; "to have a taste of your own medicine" is to experience something negative that you do to others; "a bitter pill to swallow" does not necessarily have to be a deserved experience, but is yet again another thing that we need to swallow, or tolerate. I was actually partially inspired by Alison's post about "Processing Info is Consuming" so credit goes out there!
Eating crow is a negative expression that means "to be forced into doing something humiliating or disagreeable, or to be proven wrong." Crows already have negative associations, such as being carrion eaters, symbols of death,and troublesome pests. Eating humble pie seems counter intuitive, especially with the word "pie," but I found an account that says "humble" comes from "umbles," the innards of a deer, which was used in a pie for servants and lower class people. From here,

The word umbles is a variant form of an old French term noumbles, (originally from Latinlumulus, a diminutive of lumbus, from which we also get loin and lumbar); umblesseems to be derived from numbles by the process called metanalysis which, for example, turned a norange into an orange; umbles also sometimes appeared in medieval times and later in the form humbles. Contrariwise, the word humble(originally from the Latin humilem from which we also get humility) was frequently spelt and pronounced “umble” from medieval times right down to the nineteenth century. So the figurative sense of umble pie could have appeared at almost any time since the medieval period; indeed, so close is the association that it is surprising that the OED’s first citation dates only from 1830. 

Interesting! But that website looks sketchy and I need to research more, because OED didn't say anything about this... but anyways:
I believe that this association comes from a (natural, but who's to say what's right for everyone?) aversion that most people have towards bitter foods. Evolutionary, avoiding bitter foods could have prevented poisoning (as in the case of inedibles or of toxic things like fungi). Many foods that are inedible and are poisonous are basic, such as soap, paint, cleaning chemicals, hairspray, etc and have bitter tastes. Bitter tastes also usually induce frowning or grimacing, which could be part of the negative association.

3.
Other considerations:
"You're nuts/nutty"
"You're so fruity!
"You're a fruitcake"

"To go/be bananas"
Be right back-stressful morning, hopefully can analyze this later!