What sould i do about my horse that always pulls me around to eat gr?

my new horse roxy is a wonderful horse...... exept for this one little thing she has going on all she wants to do is eat! gr, hay, grain, you name it. and yes i know horses like to eat but its gotten so bad that i cant even go into my areana to ride her with out her pulling me around the ring and looking for gr. i have tried many things pulling her up and scolding her. i had this cain i youst to use for my stallion appaloosa arund his noze i never heart either of them with it its just an extra thing i have incase they get out of control, and i used that on her but it didnt work either, so i am not sure what else i could possible do does anyone have any ideas?