Dig this fun piece at the Smithsonian on the origins of food idioms:
Sowing your wild oats: According to World Wide Words, a blog written by British lexicographer Michael Quinion, this expression dates to at least the 16th century, and refers to the worthlessness of wild oats (the probable precursor to cultivated oats) as a cereal crop. Therefore, a young man who sows wild oats is—ahem—spreading seeds without purpose, or otherwise pursuing idle pastimes.
Upper crust: In olden days, the top half of a loaf a bread was considered better, and was served to the nobility. (Source: Mad as a Wet Hen!)