It is a hand made wicker basket from Charleston, SC. I was looking through some old golf magazines and came across a Stumpfs Magazine that sold all sorts of golf course equipment. I was looking for something different for my course and soon realized that "back in the day", pennants, streamers, balls and baskets all adorned the tops of flagsticks--no real standard flag early on.
In this catalog from 1931 or so they even sold "Wicker Balloon Baskets" for $7.50 which look just like those that adorn Merion's East course. Interstingly, the advertisement trumpeted the fact that the baskets were very visible compared to flags.
In fact, on a parkland course with very little wind, I suspect the benefit of being able to see the basket as opposed to a limp flag was more of an advantage to some than the disadvantage of not being able to guage the wind!!
On calm days it's easier to hit the basket with your rangefinder too
Sea Island in Georgia also uses baskets and a public course off of I-85 also used them--Southerness??, maybe.
My baskets are a little different--I use yellow instead of red/orange paint
and they are a little larger than Merion's. We will have Rivermont baskets 2.0 that will continue the weave to the base and perhaps be a little smaller and sturdier. I have been pleased that our order of 40 baskets has made it through a full season in decent shape!