Sister-in-law gift issues

knottie413582550d16e81f

My sister-in-law keeps buying my 18 month old unicorn toys, stuffed animals and clothing. I made it clear from before she was even born that I did not like rainbows, glitter, ruffles, unicorns and super girly things. I have always been a tomboy myself and that is how I plan on raising my daughter. I want her to be exposed to science and nature. She loves being outside and getting dirty, deer and bears and has pointed out the moon since she was 6 months old. She is a very smart little girl. If she decides at the age of 4 that she's obsessed with unicorns then I will tackle that bridge when I get to it but as for right now I am not giving her any of the stuff my sister-in-law buys for her. My question is do I tell my sister-in-law that I am just donating all of the things she buys or continue letting her. She knows for sure I do not like it.