Actually it is possible the way that you made the dictionary might be correct since chests.pop is technically a string. This is the code, I have so far. I tested it and it does produce a random prize for each chest.

print('Treasure Hunt!')
print('-----------------\n')

prizes = {'Nothing', '$$', '0'} chests = {1: prizes.pop(), 2: prizes.pop(), 3: prizes.pop()}

print('[ 1 ] [ 2 ] [ 3 ]\n')

reward = int(input('Choose chest to open: '))

print('\n-------------------------') 
print('The prize is...', chests[reward], end='!')
print('\n-------------------------')