Clay soil is heavy stuff. It feels sticky when wet and turns into a brick when dry. Most plants hate it because their roots cant breathe or push through the thick mess. But clay tolerant plants are built different. They have strong roots that can handle the squeeze.
These plants handle clay a little better than most. Some of these don't mind wet feet in winter or hard ground in summer. They are tough as nails. Adding some compost helps but these legends can survive without much fuss.
Growing these means less digging and more living. They do the hard work so you dont have to.
Obviously it's better to improve the soil, but you've got to start somewhere.