SCAMMERS

I met this problem today and I never think it’s ever happened. So basically I sell my prom dress and like the pictures y’all see, she said she will pay extra because she wants it as a gift for someone. I gave her my address and phone number. and the last picture is a women tried to do the same thing but now I feel like something is not right. I haven’t received any check yet but I’m kinda freaked out. Can someone explain? and your solution? Thank you.