There’s a very obvious meaning to this brief incident, but the story is far richer with the proper context. For once I’m going to link to an outside source with more details than I have room to share here. Please note that my own research supports this outside source, bringing together a lot of information I found scattered.
The Second Temple (Ezra’s Temple) was likely built on the same foundation as Solomon’s Temple, but nowhere near so grand and beautiful. Herod came along and, as part of his political efforts at self-aggrandizement, found a project of expanding and beautifying the Temple would make a name for himself and endear himself to some of his political resistance. Being quite the architect himself, Herod designed the means to expand greatly the Temple Plaza with massive stones, so that the terrace was far larger than ever before.
This included a far larger Court of Women, where we find Jesus sitting after a long day of debating with the Pharisees and Sadducees, mixed with extended teaching sessions. In this part of the Temple grounds sat thirteen chests to receive money offerings for the continued upgrading and maintenance of the Temple. Each chest was locked and chained in place along the colonnaded sides of the Court of Woman. Each had a trumpet shaped brass receptacle on the top so that coins could be dropped in, but a thief’s hand could not reach down into it. They were also guarded by the Jewish Temple police. Jesus sat where He could see people approaching one or another chest at random and dropping in coins.
As Mark records things, Jesus had just been warning His listeners to avoid acting like the Scribes and Pharisees, who put on a big show. There were some walking by doing just that, dropping in a handful of coins that rattled in the brass horn. At some point, an elderly widow stepped up to one of the chests and dropped in two of the smallest coins (a fair estimate in today’s US currency would be about a dollar each in buying power). That would have just barely fed her for a few days, if she did all the work herself cooking the food from scratch. Instead, she chose to fast for awhile so she could make an offering. You can bet none of the big shots were going to go hungry from their noisy offerings.
She was just like the widows whom the Pharisees and Scribes defrauded to take their homes in the previous verses. When Herod began expanding the Temple, there’s a good chance a few widows were kicked out of their homes, because this was one massive project and we have no idea what was torn down to make way. Jesus noted that this widow had given more of her self than anyone else they had seen that day. This indicates there were still just a few Israelis who understood the ancient Hebrew otherworldliness, against the leadership and rulers whom Jesus said worshiped Mammon (materialism).