On Friday evening I realized my error in my tree guessing. That is, I didn't bother going to the local nurseries (aka Home Depot--and this is just a guess as to where the previous owners got the trees...this is mostly because everything else in this house is from Home Depot).
Anyhoo, on Friday, I went to the Walmart to get some cake decorating things, and I decided to take a gander at the various trees in stock. This is when I decided that it's more than likely that the tree in the front yard is not a Hawthorn, but a Bradford Flowering Pear Tree. Likewise the other tree in the front yard is a Shumard Red Oak.
Also, Ross told me that the Home Depot has Improved Meyer's Lemon trees (update: The Home Depot is out of them--they still have satsuma mandarins and some funny lemon) as well as Columbines which oddly (or not so oddly) grow in the shade down here. So, we'll plant some of them in our shade garden and see how they do--I just really don't want to plant Hosta all over in the back corner.