Hello Melinda and welcome to our family.
Shelby is very much a mature grey and since she has layed eggs before then I think she is nesting. The box you provided her with is sort of encouraging her to nest and she is protecting it therefore she is biting you when you come into the kitchen. I would suggest you remove the box and find something else she can get on like a playstand, something that is nothing like a box, she might be plucking herself to have material for lining the nest as some birds will do that.
Forget about trying to find a male for her, she is a pet and the liklihood that she would be receptive to a male is highly unlikely, even though they are flock creatures they do not get along with other birds especially their own kind unless they are nest mates. The egg laying and her being aggressive are directly related.