Answer:
I travel in a gaggle.
I break down buildings, I crumble mountains but you can't see me. What am I?
I cannot be burned in fire or drowned in water
The more you take of me the more you leave behind.
I am merry creature in pleasant time of year as in but certain seasons I sing that you can hear; And yet I'm made a by-word A very perfect mock; Compared to foolish persons And silliest of all folk.
hey are producers of pies and burgers and are great for tipping.