Yaupon holly/ilex vomitoria - full size, not dwarf, with plenty of females for fruiting would be a good, bullet-proof choice.
Wax myrtle/myrica cerifera is another one - both of these will reach small tree size with bushiness.
Southern magnolia/magnolia grandiflora is evergreen, and it grows fast here in its youth. It's natural shape is beautiful and would give you much better screening than you'd get if you cut off the lower branches, which also looks extremely tacky to my eyes.
Gallberry/ilex glabra is another possibility, but I've never seen any with good natural shaping - they look their best when they sprout up from burned over land, which you obviously wouldn't want to do.
How about eastern juniper/juniperus virginiana or the western counterpart?
It's hard for me to recommend anything for anybody else knowing how different the growing conditions are in different parts of the country - there are many evergreen shrubs that grow easily where I am, but they like acid, damp soil, and I don't picture that in Oklahoma, but maybe some of them would do for you. Some of them would be evergreen azaleas, starbush/illicium floridanum, leucothoe axillaris, and evergreen blueberries.
Sherry

Woodlander's - a mail-order nursery in Aiken, SC - carries red, yellow and orange berried yaupons. You could plant the variously colored yaupons if you'd like. Birds eat yaupon berries, so I especially like it.
Michael Dirr has two books, "Dirr's Hardy Trees and Shrubs" and "Dirr's Trees and Shrubs for Warm Climates" which list mostly non-natives, most of which are available to buy. His opinions are very different from mine, but his books have a lot of great pictures, and you might find something in them that you'd like.
Sherry

I was wondering about planting yaupons. Just not certain if their texture look will be compatable with the young Foster holly, pecan, and Shumard oak trees growing along the property line and almost 20 feet behind the once solid row of Loblolly trees.

This vacant half acre lot where my loblolly trees in question, are growing is in Northeastern OK.

The soil is a silty loam and situated only 2 1/2 miles west of the Arkansas River.

The lot does not flood, but the fine grains of sediment which make up the silty loam soil cause the rain which falls upon the land and storm runoff which overflows the lot, to stay on the surface much longer and only perculate down into the soil slowly. That is, unless on parts of the lot where the elevation is so sloped that the water quickly continues on as fast moving, storm runoff.

At the end of the line of loblollies, where the only two are growing fairly close, the water table seems higher, and over the last 4 years, these two loblollies have struggled from too much moisture in the soil during extended rain periods. These two loblollies had been planted at the same time as all the others, but due to their struggle to overcome the fairly high water table which begins to show up if one digs near them only two to three feet down, yet even more shallow, during extended slow rain events. These two trees have managed to survive, but are currently only about a third of the size to which the other Loblolly trees have grown.

The soil under what used to be a double staggered solid looking row of Loblolly pines is slightly more acidic due to the pine needles that fell, in fairly small amounts, to the ground beneath them. I suspect the acid soil levels in that area will continue to elevate as the remaining loblolly trees begin their stage of dropping lower leaves and branches to form tall trunks beneath spreading pine needle canopies.

Plenty of times the soil is moist, in the winter, spring, and fall, but there still are several months in the year when the soil condition would be too dry for most of the acid, damp soil loving flowering shrubs. and the area gets too much sun for many of those, which locally, need to be planted in morning sun and afternoon shade conditions

I like the Magnolia suggestion, as long as it is a cultivar which will not overpower the lighter look of the loblolly trees. maybe Magnolias like the 'Jane' cultivar. Then again, I also like the look of Chaste trees. The only thing that has held me back from planning to use those is my concern over the fact that they go dormant, here beginning in late fall, through winter and the very earliest weeks close to spring.

In fact the local chaste trees do not leaf out in our area again until mid to late May or early June.

Our summer, 8, sun exposure zone is okay for the suggested wax myrtle. Still a little iffy, though. Especially when I consider our border winter temperate USDA Zone, where, even though our winter climate averages closer to the 7a USDA temperature zones, we still get plenty shots of colder low levels of the 6b temperate zone, which occur in waves of time most often during our January and early February winter period.

Katrina:

Loblolly pine is the dominant species in my area. We tend to view it with wariness because it snaps under ice and during high winds. Here are some suggestions for shrubs and small trees that do well as companions. Just check the cold hardiness of these selections re: your conditions in OK.

Many hollies including Yaupon Holly (Ilex vomitoria) - you can't go wrong with one of these cultivars. I have 'Pendula" next to the house - it takes abuse (hot afternoon sun, high winds, flooding) and thrives.

Fragrant tea olive (Osmanthus fragrans) - Broadleaf evergreen, 10-15 feet; wonderfully fragrant for months. Fine in sun and shade. Adapts to various soils. No serious diseases. Main problem: cold. Temps below 0 F will damage leaves.

Prague viburnum - I love this little tree. It's evergreen, has beautiful leaves, is loaded with fragrant flowers in early spring. Not high maintenance. Looks good all year.

Viburnum tinus (Laurustrinus) - A favorite broadleaf evergreen, takes abuse, very fragrant in the winter. Dirr says, "Habit is upright rounded, evergreen, dense, thickly branched ... leaves are beautiful, lustrous dark, almost black-green. Pink budded flowers open white ... flower effect seems to last forever because cool temps prolong the effectiveness ... metallic blue fruit mature and persist into next flowering cycle. Great shade plant, also tolerant of full sun. Grows in gravel and clay; pH adaptable and salt tolerant. Great plant for the winter garden. Serviceable, functional, and aesthetic in one mass of green... grows 6-12 feet high, slightly less in spread."

BUT "killed to the ground in Athens GA at -3F."
Osmanthus americanus (Devilwood/Wild Olive) - 15-25 feet high. Hardy, fragrant flowers, birds love the seeds. Dirr says, "Possesses latent beauty - good choice for naturalizing in moist soils. In March and April, fragrant cream colored flowers appear ... Use in a grouping."

You have decisions to make - and maybe new plants to discover. Have fun!

Pam

What about "Little Gem" magnolia? They should stay smaller and not overtake the pines. They're also considered hardy to zone 6.

Thanks Pam. After researching, it seems reasonable for me to conclude that the Prague Viburnum is able to easily, perform well for the area in question.

The Osmanthus would be nice if our cold hardy zone was at least 7b, but it still has motivated me to check with local nursery suppliers, just in case they might have a cultivar which is more hardy to this region's 6b/7a winters.

Maybe if the viburnums work well for me, some Yaupons can be worked in among the planting area in question, without seeming to clash too much with the textures of the trees growing along the back fence line.

Might be something of interest here (scroll down for tables of suggested plants).

Here is a link that might be useful: Oklahoma Cooperative Extension Service - Landscaping for Energy Conservation

Thanks bboy