A friend needs help - from Central Texas
SOLVED: A friend needs help - from Central Texas
Aesculus. There are several native to USA and Europe, (lumpers and splitters are still discussing how many species) and hybrids are grown for different flower colors.
If this is in the wild, perhaps A. glabra var arguta, the Texas or White Buckeye. There is also a red flowered species.
If this is in a garden, A. californica is one of many that have white flowers, perhaps someone planted it.