Eating a rare flower and lead the galli to a trap don't work. The follow you for a little while but then after that they just run away from you and will not follow again no matter how many flowers you eat
To tame one of these just clear out an area of all other creatures. Then eat a rare flower so it will agro you. Shoot it with a few darts and boom it’s nocked out. Make sure you have lots of narcotics though.