Mustard Pie Spring 2018 is here!! Find at https://southernsweetchildren.com/collections/mustard-pie. Mustard Pie Clothing: Kaleidoscope of Colors, Prints & Designs. Mustard Pie Clothing is a boutique girls clothing brand that creates refreshing collection of little girl's clothes. We couldn't resist the sweet prints, lovely colors patterns and unique designs. Mustard Pie is one of the most popular children's designers. Loved for inspired prints, unique color combinations and truly fun styling that's easy to wear and looks special every day. Whether she loves the ruffled leggings, the mixed-print dresses or storybook tunics, she'll fall in love all over again every season.