Why did my cat bring me a dead mouse?

This was a while ago,and i chose to ignore it,but i want to know why she brought me a dead mouse.It was about a month ago (so late...) and i came home from school and she goes to my lap and puts the dead mouse on my lap.at first i found it disgusting,but then i decided to keep for no reason,but my mum threw it in the trash,and my cat got me another dead mouse the next day.Is it a sign or something? is it like a "hey thanks for caring for me!"? the info about this cat: In winter,she was a baby kitten,and i found her in the street,so i nursed her back to health,gave her a warm home,and i cared for her and i watched her grow (oh..memories...) her name is Michi,pronounced Mee-shee...so,is it like a thnxs for saving her when she was a baby? or is she just tryin to show off that she could hunt better thn me lolz...(no,i dnt hunt...) so...why? (p.s.im not the brightest sooo....dnt judge me....)