Can I paint team logos or characters on walls legally?

I painted a Cowboys star on my wall, a Bengal on my friends wall, and a picture of Elvis on my moms wall. I didn't charge anything for it. It was for friends and family, but they all came out really good, and I've been told I could make good money for it. But they're licensed logos, so can I? Is there a way around it? Maybe doing the labor and artwork for free and charging a fee for the mandatory sealer?