Does anyone happen to know what this strange holly-type plant is? Do birds like it?
Mahonia, possibly Mahonia bealei but there are many...
Yes, birds like it. And that is likely how it is spreading and becoming an invasive in many states. It's not really a problem here in Northern VA, but I understand it is further South.
It's a very spiny shrub and probably useful in some landscape situations.
'....probably useful in some landscape situations.' In climates where it is not a problem re-seeder it is a highly appreciated shrub for its architectural foliage and its deliciously fragrant yellow flowers borne in mid-winter and very early spring. The spines are not a problem except for pruning and then no more that pruning a rose or holly bush. It and various other Mahonia species and hybrids are common and valued shrubs in the UK.
Here is a link that might be useful: Mahonias
Thank you everyone! Mahonia bealei looks EXACTLY like what I have. I think it's a keeper. :)