Most commercially available terrestrial mosses are not suitable for indoor cultivation. The main reason is that they really do best with humidity and a cool temperature range from the mid 60sF down into the low 40sF. However, there are some tropical mosses available but then you still have the issue of humidity and providing a cool down at night for them (down into the upper 50sF).
But there is a group of aquatic to semi-aquatic mosses that can serve your purpose and will do quite well in a planter that this partially filled with distilled, rain, or r/o water. The most common one is called Java Moss.
Will growing in water the moss will grow out onto any nearby surfaces, such as a piece of wood.
Mosses do not flower but there is another aquatic plant that may be found on the net at a water plant retailer caller Bladderwort. Since the plant is a carnivorous plant it may also be found under Carnivorous plant retailers. There are several species. To get it to flower you really need to provide adequate light. Check the link below for a couple of images. These flowers are very tiny!

Here is a link that might be useful: Common bladderwort