Could be Lunaria (silver dollars is the common name here) or could be garlic mustard????

Alliaria petiolata, garlic mustard

Hi and thank you so much! I have been invaded with it and need to get rid of it. Isamae

It's garlic mustard. Act fast as they set seed pods that will scatter in a couple of weeks, maybe in June, if you are in Upper Penn.

If you are being "invaded" as you say already, it sounds like you got one or two, that you did not notice, and then they scattered seeds, and they are all coming up now this season. This stuff can be a nightmare. It can wipe out woodlands. Google it and be amazed.

Here is some information about Garlic Mustard

Here is a link that might be useful: Garlic Mustard