horsetail is the only one I know of that works well because of the silica content

some herbs will actually tarnish silver because of some of the cemicals that will react with it that the contain, more willreact with ferrous alloys and copper (and even aluminium) based alloys even more strongly. Many plants contain phenolic compounds such as tannins, flavanoids, and others which are the antioxidants that often make them so beneficial medically but these also react with metal ions to form insoluable dark or coloured compounds. Iron plus tannins gives gall ink used for centuries. Many natural dyes are based on the combination of a plant constituent with a metal ion (mordant) to form the pigment that bonds to the fibres. In though I use stainless utensils when working with herbs (and to stir my herb teas) I often have to polish off the gunmetal blue-grey patina that forms after some while.

I've always used good old fashioned baking soda and a damp cloth or toothbrush to polish my silver or stainless. It gives a high shine to silver far superior to other cleaners and doesn't really require much elbow grease nless they are VERY tarnished and is non toxic and doesn't promote oxidation. It is also very fine and gentle and can be used on electroplate so long as you don't go at it as if you'e sanding wood! : )
A paste made with sea salt and white vinegar can remove tarnish quite easily from copper based alloys but they must be rinsed well after it is used to clean them.

I know these aren't herbal but they're natural. Maybe they'll be of use?