Hello important information!!!
Bread is NOT part of a skeleton's natural diet and feeding it to them can make them sick. Instead try: coins from countries that no longer exist, dead batteries, ballpoint pens, or brass buckles. These are much closer to what skeletons eat in the wild :)
I live in a coastal region and I generally feed the local skeletons with broken seashells collected during low tide, which are high in calcium and other natural minerals. Very occasionally, such as for celebrations such as last night's solstice, a shard of broken ancient pottery makes a great treat, but be careful, as these are sometimes cursed, and may cause issues for some skeletons.