Say "Ah"

This reminds me of someone sticking out their tongue. I don't know what kind of flower this is (let me know if you do), but it is in the back yard in one of my overgrown weed patches.

One of the past owners of my house did some great gardening; we get flowers popping up all throughout the spring and summer. Problem is, I'm not so good at keeping up with them, so I'm sure the yard looks nothing like it used to.