Per the folks at Coleman, this is probably Vernon.
From Fruit Facts: White sapote fruit ripens six to nine months from bloom. Some cultivars are alternate bearing. Fruit size varies from 1 inch to 6 inches for some of the newer cultivars. Fruit color ranges from apple-green to orange-yellow at maturity, according to cultivar. The fruit shape is round, oval or ovoid, symmetrical or irregular.. Green-skinned varieties have white flesh; yellow skinned varieties have yellow flesh. (This is a green-skinned variety) The flesh has a custard-like texture and a sweet delicious flavor reminiscent of peach or banana
.photo by Carlos Velazcos