Ne'er cast a clout 'til May be out
(clout, literally, means cloth; and is evidently being used figuratively to mean "an item of clothing". So we can render this saying as "Wait until June before you start wearing your summer skimpies")
You've got to eat a peck of dirt before you die
(If you've ever seen the size of a peck measure, you'll appreciate the point being made: don't worry too much if your fruit an dvegetables come with a little bit of earth on them!)