We use the "wild bird seed" as it's the cheapest at Walmart - $5.50 for a 20 pound bag that lasts a month or so. We get an assortment of birds - doves, bluejays, cardinals, something that looks like a bluejay but is black/grey, some other really tiny songbirds, woodpeckers, and even some crows. I'm not super on bird recognition yet, and it took a couple of weeks for the birds to notice the feeder, but now that they all know it's there, we usually have one bird or another out there at all times.
We also get squirrels, and I've thought about upgrading to a squirrel-proof feeder, but honestly I enjoy watching them eat, too.
My favorite are the doves. They'll eat seed scattered on the ground, and make some of the prettiest sounds.
We get birds trapped on our back porch fairly frequently, since we keep the screen door open (it's either that, or my daughter pops the screen loose in order to get outside... sigh), and I've gotten to be a pro at catching and releasing the poor things. I caught a small owl (screech owl, we think) a couple of months back. That was exciting!
