These two phrases are from Harper Lee's Go Set a Watchman. I'm not sure, but I guess the first one (light'ud knots) is talking about a woman who can handle problems easily and is kinda independent. As for 'hind f'omus, I guess Jim is right in his comment below that it must be "behind from us".
Here are the paragraphs:
Don’t you know how to catch a woman, honey? Women like for their men to be masterful and at the same time remote, if you can pull that trick. Make them feel helpless, especially when you know they can pick up a load of light’ud knots with no trouble. Never doubt yourself in front of them, and by no means tell them you don’t understand them.”
You’re sort of ’hind f’omus, Miss Scout. You sort of haven’t caught up with yourself … now if you’d been raised on a farm you’da known it before you could walk, or if there’d been any women around—if your mamma had lived you’da known it—”