Joan Rivers made one hell of an impression on her former ” Celebrity Apprentice ” co-star Herschel Walker … who just told TMZ a story about Joan that’s pretty awesome. First off, Walker says Rivers was one of the nicest people he’d ever met — and says he was “very depressed” after learning about her passing. Walker said,” After ‘Celebrity Apprentice,’ Joan asked for my mom’s address. Then, she sent my mom a letter saying how I was such a nice man and sent her a charm necklace by the Joan Rivers collection. So, unexpected and kind of her.”