Answer:
I am a tale in childrens' minds. Though an illusion, I occur every night. I give them a fantasy, I give them a fright. What am I?
I am flora not fauna. I am foliage not trees. I am shrubbery not grass.
Who is the most foreign visitor you could imagine?
I start with an E end with an E and have a letter in me.
In buckles or lace I help set the pace. The farther you go the thinner I grow.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.