Does anyone know what this plant Is? Is it a weed?

Sue Brown2

Weed?

Fire

Looks like garlic mustard. Young leaves are delicious in salads. You can cook the leaves like spinach or make a pesto with it. Great habitat for butterflies. The flowers, not the pesto.

a1154

Also jack by the hedge. It’s definitely a weed when it’s in my garden.

fidgetbones

Orange tip butterflies like it. I remove it when the annuals are ready to go in.

Silver surfer

Alliaria petiolata   has many common names including  Jack-by-the-hedge. Other common names include Garlic Mustard,[2] garlic root, hedge garlic, sauce-alone, skyut, Jack-in-the-bush, penny hedge and poor man's mustard. 

https://en.wikipedia.org/wiki/Alliaria_petiolata