Congratulations!! That's wonderful. I adore them too. I find it funny how they sometimes run off other birds. I saw one last year doing this and it wasn't even at feeders he ate at. What I found funny is that he only did it sometimes.
Yeah; Mockingbirds are like the terrriers of the bird world. They might not be the biggest and baddest, but they believe that they are so completely that they are able to convince the bigger and badder birds that they are.
I keep a pan of sunflower seeds and peanuts on the back porch railing and I just watched a Titmouse grab a peanut, make a hole in it so he could get a good grip on it and then fly off with it. These guys are so funny.