Puzzle.
My first is simply a vegetable, delicious, round and green. – Pea / P
My third and fourth are sound asleep, as plainly can be seen. – ZZ
My fifth is fifty, clear enough for any riddle-setter. – L (Roman numeral)
Two of my second on their sides will give my final letter. – E (Take 2 U’s and stack them sideways.)
Now that my second has my parts, fit them together well. – Now that YOU (u) have my parts…
You see me now before your eyes; it’s plain for all to tell.