Red-tailed Hawk dive bombed by crow and other birds -- near home

Today has been good for birding so far.  I have had some of my 'regulars' such as crows, starlings, pigeons, etc.  I had a Red-tailed Hawk fly directly over me, and away.  Also have had a male American Goldfinch.  A Fish Crow overhead (Fish Crows are different than what I usually call 'crows' which are American Crows).  I had an unidentified bird (between sparrow and meadowlark size, it went unidentified, it had a yellow belly).  I kept hearing several pretty songbird calls in my yard, I wasn't quiet sure what it was (or what they were).  I found a Northern Mockingbird mimicking different calls.  It stayed in a tree for a while, and then flew across a field, and started dive bombing a crow.  The crows were calling loudly (others were calling).  I think the mockingbird backed off, but what was interesting is a Red-tailed Hawk came in patrolling low.  Then the crows got on the hawk and starting dive bombing, and chased the hawk across a field.  It's been interesting for birding, but unfortunately no good bird photos today.