"18 and now you're in the big girl shoes for real," she captioned this pic of a baby Lily. "I love you so much @lily_beckinsale. Nothing has been better in my life than being your mama. Happy happy happy birthday to my favorite, funniest best person in the world. P.S. We will obviously get you better shoes those are hideous I don't know what I was thinking." That had us tearing up. Lily, however, had a standard teen reaction. "Gaggggged mother!!!" the college-bound kid responded in the comments. We think that translates to "you have embarrassed me beyond repair, Mother, but I'm secretly touched."