This week's CUESA newsletter had a write up of subtropical fruit grown by Brokaw Nursery. While they like bringing fully ripe mangos fresh from the tree, I might suggest asking them if they will sell baby green mangoes.
These are one of the best new things I've eaten in Guatemala. They have to be baby when the seed is still soft, sort of like a chayote seed. Once the seed is too hard to cut through, it's all over and the mango isn't worth it .
But baby ... oh baby ... crunchy with a little more texture and less water than a cucumber. They have a surprising salty-citrus taste. Don't eat the seed because it is really, really bitter. The taste is totally different from green papaya.
Anyway, it doesn't hurt to ask
My post with photos of baby green mangos