This is a new tee from J.Crew (item #15285), in white. It was marked $36.50. I'm calling it the Watercolor Floral tee, as it is similar to the Watercolor Floral Pencil Skirt. I believe this is made out of the painter tee material. I accidentally picked this up in a size larger than my regular tee size, so I can't really comment on how true-to-size it is. I think it looks okay, but my PS thought it looked too big.
You might have guessed that I left this tee at the store (and you'd be correct!). I think cute tees are a good wardrobe staple, but this tee was not my cup of tea (ha!), and I know I'd hardly ever wear it, if ever.