Should I gift my boss who hire me?

She hired me as admin on hospital and I think I will get my paycheck in the next few days and Im thinking of buying her brownies or take out fastfood as a sign of gratitude for hiring me? Or does it makes me seem like Im sucking my boss? I also think what will my co worker will think of me if I give my boss a gift?
Should I gift my boss who hire me?
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