Would love to know if this is a weed or not! thanks very much.
If it's a weed it's a pretty one :)
Alliaria petiolata - Garlic Mustard. Massive weed trouble in the US.
oh sad. these are all over my raspberry patch (the one thing I knew was growing in my backyard!) I guess I'd better rip them out. I thought they were new raspberry plants coming up until they flowered. thanks for all the help.
Here is a link that might be useful: PCA - Garlic Mustard