1- I stopped at a bank in a really small town and asked for half dollars, or the big dollar coins. The teller looked at me and pulled out what she had and laid them on the counter. Then she looked at me again and called the manager. She came over and teller asked if she could sell the half dollars. The manager picked up two obviously silver coins and said, "sure he can have the rest."
2- Another bank I asked for halfs, the teller said sure, and handed both to me, the second was a walker. He was hesitant to sell it to me afraid it was counterfeit. After I assured him it was real he was willing to sell it to me.
3- It has really struck me of late how truly ignorant the tellers are of cash. Asking for $2 bills or half dollars, or large dollars drive them right round the bend. Counting $10 in $2 bills can really clog their brains.
4- Not just tellers, but cashiers as well. try paying with half dollars. Most take several minutes staring at it just to figure out what it is, even when I tell them.