OK, this works. Take your lunge whip with your when you go for a walk with your horse. When you get to the grass, if he makes a nose dive for it, do not pull on the halter but give him a tap on the hip. The whip keep you out of kicking distance. If a tap doesn't get him moving, then try a firmer one. If he circles you that's ok because at least he's moving. Give him 4-6' of lead. When he stops and only if his head remains up, take him to the grass, bend over a little, tug lightly on the lead to invite him to eat. Teach him that when you click or kiss, not pull, his head is to come up as you have signalled him to move his feet, or it will be followed by a tap on the bum. You need to polish your groundwork. Stand about a foot off his shoulder and face it. Lightly pull his nose toward your hip. If he is resistant you will get only an inch or two before he demands his head to be straight. You need to be patient and ask again. Try small intermittent pulls. He doesn't really know what you want but the more you work at this the more he will begin to think it's not so bad and will begin to relax. Don't try to force his head around or hold on to it when you feel the resistance, Try to keep a light touch. When he's not to bad on the near side, try the off side. Most horses initially are very resistant on that side but again, patience will pay off.