A clump is a group of similar things, very close together and hard to separate. The picture is of a clump of yellow flowers.
A crowd is a large group of people. Generally a crowd is a group of people with no particular order, jostling together.
You can also use crowd as a verb, as in "to crowd in together" which means putting a lot of things in a small space.
Dis forDeck (cards)
A full set of cards, as purchased from a shop in a box, is called a deck or pack.
Dis forDrove (hares)
A group of hares is called a drove. Sometimes they are called a husk.