What are Meredith Masony's top-selling 'Things Moms Say' merchandise items?

I'm sorry, but I don't have the specific information on the top-selling 'Things Moms Say' merchandise items by Meredith Masony. However, I can tell you that she has a variety of merchandise available, including her book "Scoop The Poop", which was on sale for Mother's Day. It's always a good idea to check out her official website or social media channels for the most up-to-date information on her merchandise.

Would you like to know more about her book "Scoop The Poop"? Or perhaps you're interested in her videos on motherhood?