Okay, I am certain I have the answer, but I'm having trouble making some of the clues fit.
The answer is
Preposition, adverb, and suffix too,
It relates in every situation to you.
"on" is a preposition, adverb, and suffix. Not sure about the second line.
Veggies of the ground or fruit of a brood,
Drop the first letter of the scrumptious food.
"Tomato" is the answer to the first line. Drop the "t" and you get "omato"
A master of writing and founder of fear,
Whose works are always lurking near.
Who else but Edgar Allen "Poe"?
The seeing spots on the face of a bird,
Is an epithet for the shortened word.
Iowa is considered a "flyover" state, and someone flying over it would have a "bird's eye" view of it. The abbreviation for Iowa is "IA".
The word is important in farms or magazines,
It means what it says and says what it means.
This stanza is a reference to onomatopoeia as a whole. Farm animal noises are described using onomatopoeia ("Pig goes oink, cow goes moo"), and the second line is basically a straight definition of onomatopoeia! Not sure about magazines, though, unless it's a reference to gun magazines and sounds like "Bang!"
The clues I'm not sure about are "It relates in every situation to you", "fruit of a brood", "Whose works are always lurking near", and "magazines".
Any help on filling in blanks would be appreciated, but I would be shocked if this isn't the answer.