You should be old enough to enter into contracts. At 20 years old, you are now considered an adult; but depending on where you live, they might have local laws saying you have to be at least 21 to enter into certain contracts.
You have to be 18 to pawn something.You will be required to show ID in which they will write down all your info, or make a xerox copy of it.Take your stuff to the pawn shop.You will be given about 1/3 of its value in cash.If you do not return the items within a specified amount of time, they keep your items.You can also, ask them to buy it outright - also 1/3 of value./
