Not much is going to survive the birds really. You will find that you have a small stomped spot from the ground feeding birds. Plus I would want to be able to clean the area every once in awhile. With my feeders, which is primarily black oil, I don't have to do this often since black oil shells are so thin they blow away or rot rapidly, but I am not sure about safflower. Black oil also has a pre-emergent coating naturally on it's shell which makes growing anything difficult. I don't know if safflower does. There is some lantana growing under it, but I didn't plant it there and I will eventually get rid of it - it's an invasive here.

If you really wanted to try something, thyme may be a good choice. It's tough, very short so you can still see the birds. Thyme takes a bit to establish but once it does dig in, hardy as the dickens.

Violets sprout everywhere - look into that before planting. Pennsylvania sedge, which is a hardy plant, would be a better choice if it were my yard.

Under my Black Oil Sunflower feeders on a feeding station the ground is bare. When the hulls begin to build up, I clean them out easily.

I have few or no plantings around the feeders and bird baths, and like to keep it clear approx 3 feet or more around them for foot traffic. It makes it easier to fill, clean, and maintain the feeders and baths and in my case rake up the Black-oil Sunflower hulls. It's also nice to have a clear area for the ground feeders to eat what falls on the ground.

I also keep it clear underneath a thick stand of evergreens and shrubbery about 10 feet away from the feeders, and sometimes scatter seed or tidbits under there for the squirrels and ground feeding birds. The birds love this vegetation because it gives them lots of cover and a place to escape any threats while feeding (perceived or otherwise).

The Pennsylvania sedge mixed with rugged low growing wildflower(s) sounds nice. Violets are so pretty but they are vigorous spreaders. Low or sparse plantings are safer for the birds because cats can't hide in them and ambush the birds. Some edging, wood chips, flat stone, etc. can give the area a more finished appearance.

You know it's funny because I was wondering about this exact question also. I have found safflower very effective because I can put it in a perching feeder to attract cardinals and grosbeaks without attracting grackles and starlings. I have found though that wherever I put the feeders the plantings underneath get trashed. At the moment I have an ugly bare patch in the lawn to contend with.

I was actually thinking of planting some vinca minor/periwinkle which is a pretty tough ground cover. Any thoughts on that idea?

I have my most of my feeders in/next to the forsythia bushes at the edge of the back yard and the bushes provide good perches, cover and protection for the birds, squirrels and chipmunks all year long.

I appreciate the comments. The issue is now moot because I've decided to stop feeding safflower until September. I still have nyjer seed, suet, and grape jelly -- but those don't make a mess on the ground. For now I'll just let my mix of grass, violets and misc. weeds that make up my lawn grow back into the bare spot. Maybe I'll plant thyme and violets in the fall.