Lambslove,
Sorry to hear your neighbor doesn't want to get along with you. I wouldn't take her leaves as it would only give her another reason to be angry with you.
Something you may wish to try though is to show her some acts of kindness, rather than just being kind. Like if you grow vegetables in your garden, see if she might like a few. Tell her the Lord has blessed your garden so well that you have more than you need and she's welcome to some if she would like. If you only grow flowers, and know how to dig up and divide the plants, maybe let her know your planning on doing so, and see if she might like you to plant some of the extras in her yard for her, or if she would simply like a few. Just make the offer, if she rejects it try not to take it personal. I can't promise you any of this would work, but it is worth the effort to at least try. The reason she may have taken offense when you mowed her lawn, was because she felt she had no control in the situation. 9kind of like when she lost her husband) It sounds like she has trouble just trusting others.
Here's a story from my childhood about a mean nasty old lady that lived down the block from us. ok so she wasn't as mean and nasty as we thought, but here's the story
My brothers and I used to play with some kids about a block and a half away from our house. There was this one old lady who if we went onto her front lawn, or played too close to her yard, would open the door or a window and yell at us. "Get out of my yard! You kids, stay away from here!" Well children don't always come up with the best solution to these types of problems. The other kids showed us what they did for revenge, and we quickly followed suit. It seemed the way to get back at her was to sneak up to her house and knock on the door and run.
It wasn't long before we told our parents about the mean old lady, and what we did to get back at her. Our mom asked where this lady lived. When we told her, her jaw dropped and she said "You kids shouldn't be doing that! that lady is your Great, Great, Great Aunt!" A few days later we were taken over to her house so we could visit her, and appologize. I was half embarassed about what we had done, and half afraid at how mad she would be at us.
As it turned out she wasn't angry with us at all, she was very sweet. She had a hard time getting around, and we learned that she went to bed real early, and it wasn't that easy for her to get out of bed and yell at us. All she actually wanted was for us to be quiet so she could sleep. In fact she didn't mind at all if we played in her yard as long as it wasn't when she was trying to sleep. We learned to show her more respect concerning the hours she slept, and were careful to not make a bunch of noise around her house during those hours. Her back yard was beautiful and I learned to enjoy hanging out there, and kept her birdbath filled for her. We also learned to help her out with many other things she had troubles doing alone.
I know this doesn't realy pertain to your situation, but thought it might be fun to share anyway.
I'll pray those leaves blow over into your yard heehee! I also pray your neighbor will learn to open her heart back up to others so she can see that not all people are out to hurt her.