Silver is often a consolation prize for a mediocre turn. Threads have ensued about silver/terminal openings vs. 2terminals, silver/potion openings, whether silver is worth getting in the mid-late game at all. Silver gainers like Explorer, Trader, Trading Post, and Bureaucrat are often weak. Other ways to gain silver are Workshop-like effects, JOAT, Upgrade and Remake.
Some ideas that came from the fact that silver is always available. Names are an afterthought, sorry if I copied yours.
Jeweler?- 6 cost.
Action
Name a Treasure card. That Treasure produces an extra 1coin this turn. Then, +1 Card.
Inspired by Coppersmith. Adding value to Silver alone likely leads to dumb Big Money games, and giving players the choice makes the math of deciding what to choose easy. Adding the +1 card after the naming and making it compete with Gold often makes the player feel smart. In a hand of Copper, Silver, Gold, Jeweler, Estate: if you want a province, you name Copper because drawing a gold or silver gives you 2 coin anyway.
Whitesmith? - 4 cost.
Action
+2 Cards. Reveal any number of Silver cards from your hand. +1 Action for each Silver revealed.
What is this card for? What card combinations break it? I don't know, but it is decently powerful in most weak boards. Silvering works best if you have no villages available and are choosing to Big Money. Engines might not pick up silvers usually.
Villain? - 5 cost.
Action-Attack
+1 Coin. +1 Buy. Each other player gains a Silver, placing it in their hand. Look in each other player's hand; choose 1 non-Victory card and return it to the Supply.
This card is likely going to cause people to freak out. It lets you take away people's most-wanted card! Unfun for new players. Like Saboteur, but with an exception for victory cards. In boards with Villain, getting double terminal in hand is okay, because the attack either doesn't hurt you or resolves the collision itself in hands with 2 terminals. Hitting a 5 cost attack is potent, hitting a Gold reduces the hand's coin output by 1, but 7+ cost cards instantly become unsafe. The card encourages buying 2 mediocre cards over 1 strong one. Even if you are hit with this attack multiple times, the worst thing happens the first time, and you are left with a silver for every card it hits, leaving you a hand like Silver, Silver, Silver, Copper, Province in the mid-late game. Schemes are good protection, Alchemists are vulnerable, and Herbalists (another +1 coin, +1 buy) might endanger your Treaures, and high value villages (Bazaar, Festival, City) might be pulled from your hand if you have 2 terminals in hand. Until recently, I had it trash the cards. In long multiplayer games, the silvers might run out, resulting in that version turning deadly.