@DLHOCNT has a point. Do not try to pick them up. I raised mine from chicks, they imprinted on me, and will run after me when I walk through the yard. They
put up with my picking them up, but they don't like it. So I only pick them up to help them, such as if they are stuck somewhere high, and aren't sure about how to get down. They flew into the snow a couple times this winter, and were obviously unhappy, but unwilling to move through it, so I picked them up to move them.
Sit quietly. Bring treats. Move slowly, be gentle, speak softly. Sit for a LONG time. Sometimes, it takes them a half hour to finish their scratching and come over to be petted. Sometimes, they run right over. You can't
force them to learn you mean no harm -- they need to learn that at their
own speed. And they will, if you are consistently slow, gentle, and quiet. And bring treats.
This picture is from fall, but she still comes over to sit on my lap and be petted.