Happy Mother's Day! Celebrities such as Michelle Obama, Gigi Hadid, Drake, and Jennifer Lopez are honoring their moms and reminiscing on precious memories with sweet Instagram tributes. "Mom, you are my rock and my best friend, and you have been a guiding light throughout my life," Michelle wrote to her mom, Marian, on Friday. Gigi gushed over her mother, Yolanda. "Best I could ever ask for. ❤️ Happy Mother's Day to the one I'll do my best to emulate," Gigi wrote on Sunday. "I love you beyond words @yolanda.hadid you are a superhero!!!!!" Keep reading to see how more stars are celebrating the special holiday!