Summon Nobles to Trade Posts and then enter the Market. Tap on your Noble(s) and task them with Trading either Food, Stone or Wood for Silver (or for another resource, depending on your role and talents).

 

Trade posts are also excellent places to meet new people and interact with their Nobles... Make some babies, do some bribing, maybe gather some intel on a potential new friend or foe.

 

A portion of the Silver paid for every trade goes to the alliance or family that owns the capital city the trade post is located in. Taxes are paid out daily.