Bet that mare is laughing the whole time too! The only thing I've found that worked long term is just walking them down. Start in as small an area as you (she) can, then pretty much keep walking up to them while visually ignoring them. By which I mean, look off into the sunset, stare at your shoes, you could care less where that horse is. At the same time maybe take a step or so closer. Plan on spending as much time as it takes. If they let you get right up to them then run off, just keep a steady pace after them and when they want to stop and taunt you again, send them off at a trot. Kind of like round pen work.

When you can stand by them, scratch them on the neck and walk off. Do over. Slip halter on, make them stand a minute, drop halter while maintaining control over them. Then YOU be the one to walk away. More than likely this will have to be done more than once. My guy finally decided it was not nearly as fun when I didn't run after him and play the game. And he got tired pretty quickly of being kept moving when it wasn't his idea. It took a few sessions but mine will generally come up to me in the pasture and no trouble catching. She'll just have to stick with it. Explain to her how to use her body language to control which way the horse moves too.

Good advice above.

I've also just put chair out in the middle of the pasture and sat down. Read a book, listen to your Ipod. When the horse come to check you out, Stratch it's nose, maybe give it a treat, then ignor it.  After ignoring it enough, you can probably catch it, reward it with a good scratch  and turn it loose. Pretty soon the horse sees getting caught as getting some love or attention and not with working.