Since you're trying to sell the house, I would try to use the area to show potential for gardening. I'd plant an edible cover crop like bush beans in wide rows. It will look nice but you or the realtor can explain that it can easily be weedwhacked and covered with sod. That way if they want to try gardening they have a yummy crop already going and if not, they have great nitrogen fixers getting the spot ready for grass.

Indoor, as in greenhouse, would give you maybe enough space and light for herbs. But I suspect many culinary herbs (which love full sun) will not fare well in a small indoor, not greenhouse type of garden. Check with potential clients to see if there is a market for your products before investing too much $$$. Farmer markets and road-side stands may be another potential outlet but again, check into it before investing any money. FataMorgana ps....there are books on growing herbs for cash. Check out what the booksellers or local libraries may have for books on the subject.

We've used red clover for this purpose more than once, in a similar-sized area. Plant in September or as soon as other plantings are removed, you need clover inches high in order to survive some winters. Spade it under in late March or April. This is a fairly coarse ground cover, it needs several (3-5) weeks to decompose. Grass clippings are fine, watch out for too many grass seeds being introduced.

better than a cover crop with no seeds is leaves. When we first moved here we had very poor soil. What we didn't know is that the previous owners of this subdivision had sold off all the top soil. We wanted to grow a vegetable garden but nothing could grow in our mostly clay soil. We had a friend who had lots of trees on his property. We told him we would gather all the leaves if we could have them. He was happy to give us the use of his mower to avoid the work. The mower broke them up and blew them into rows. We bagged them and brought them home and dumped them on the garden. My husband tilled them into the soil and the next year our soil was better and most of the leaves had either broken down or been eaten by worms. With leaves and what compost we could make our soil got better every year