I think it is dill, like used in dill pickles..

Judging by the arrangement of the fruit it appears to be something in the mustard family (Brassicaceae). Dill would have flowers and fruit in umbels.

Descurainia sophia?

Interesting... I live in Las Vegas, NV, so I'm surprised that there's dill growing wild in our backyard. Maybe it's from the last owners of the house. Oh, well. As long as it's not poisonous I don't mind. Thank you for answering my question everyone! =)

The silique indicates a Brassica, not Dill which is an Umbellifer.

Thank you. I took a close-up of the leaves. Does it still look like a Brassica?

Definitely Descurainia sophia.

lycopus and nonmember are both very experienced ID'ers. I'd listen when they suggest something.

Perhaps the term Brassica is what's causing the confusion, bignarutofan19 . It's a whole genus of plants within which there are many species, one of which is Descurainia sophia. If you look at the flowers they'll have 4 petals in a cross arrangement. Another name for Brassicaceae is Cruciferaceae because of this typical flower arrangement.

Here is a link that might be useful: Descurainia sophia

Thank you all for your responses. I looked up the plant nonmember said it was and that's definitely it, and it's edible! Can't wait to try it in a salad or stir fry. I think I'm going to let one of them go to seed so I can grow more. That is, if I like the taste of them, haha.

Keep an eye on it if you intend to let it go to seed as it is not a native species and may become invasive. Check out the link below.

Here is a link that might be useful: Flixweed