Our mystery seed from last week was most likely from Indian hawthorn, Rhaphiolepis indica or a similar species/hybrid.
Indian hawthorn is a shrub originally from Asia that is widely planted as a landscape plant in the south. It has delicate pink flowers and tolerates being severely pruned or sheered.
I was not able to verify the exact species/variety of the plant before my son removed it (the photos above are from a neighborhood plant), plus I was not able to find an image of an Indian hawthorn seed on the Internet.
Was my son correct? Is this an Indian hawthorn seed?