after you found the adress from a reward, you can change its value, right?
long press and then go to the address list, you'll see the same adress/value you just edited, and right next to it (in my case the one above) you'll see this other integer number (followed by a "D") which is the code for the reward type.
if the reward you got is gold, there is going to be a "1D" right there. 2 for gems, etc etc
so you can change it to "2" and get gems instead of anything else..
remember to reopen expedition mode to check any changes
probably you cant get cards this way, but it works for tickets, chests, gems and things like that
So get your million gems before playing with weird rewards