Moved to Texas when I was 13. We had a housekeeper who would make delicious things from dewberries — pies, cobblers, etc. I'd never heard of dewberries prior to that. Now I know that they grow wild all over Texas.
Dewberries are similar to blackberries. However, dewberries grow more like ground covers whereas blackberries grow more upright. Also, dewberries have spiked stems that look kind of hairy. They also produce fruit earlier than blackberries.
I don't know what kind of property you have, but if it's big enough to allow the dewberries to grow, I'd keep them. They are truly delicious.