From what I can tell, your mare sounds a lot like my younger one. Willing and brave, but just doesn't have the experience.
The thing that I have found helps is to keep her busy. She likes to think and she likes to know that someone else is always in charge. She's a type of horse that doesn't do well when you play into her fear and let her stop and look (she just thinks that means there is something to be scared of), so whenever we get in a really "scary" situation, I ignore her and give her something to do. Randomly, just make her turn this way, turn that way, stop, turn this way again, leg yield over her, circle here, I don't care what you're thinking but you're going to do what I tell you, bend a little, circle again...etc.
I have also found that getting in her mouth and 'pulling' her around doesn't do a whole lot. It helps when we're passing directly by something that she wants to look at, but if we're approaching it on an angle or somewhat directly, it seems that if you pull on her mouth, it just gets her more worked up and more nervous. She responds so much better to gentle leg bumps and slight tugs on the reins as opposed to pulling her entire head.
And I somewhat agree with lilruffian-it's ok to look at the scary object, but don't you "lock onto it" or tense up. The horse always knows what you're looking at and how you're feeling about what you're looking at; don't give her a reason to think that you're worried about anything.
Good luck, I know how frustrating it can be. Just keep riding and perservere. You can do it.