Guild Wars 2

For example: Omnom Berry Bar (30% MF) and Omnom Berry Tart (30% MF).

Would that give me 60% MF or would one just replace the other?

Also, what are the best MF consumables to stack (assuming they do so)? :}

only one nourishment can be active at a time, one would replace the other

Omnom Berry Bar and Magic Find Booster from the gemstore/black lion chests plus the magic find guild banner buff on top of all your magic find gear.