A few thoughts on the mustard seed. It is the yellow one in the canary seed packet. It is very small, but it is not the smallest. The seed for the Sequoia, for example, is smaller. In Jewish Law, the mustard seed was the example of smallness when considering ritual impurity from bleeding. If you cut yourself shaving, for example, the cut had to be larger than a mustard seed to be ritually unclean. This gives rise to modern English Law that "the Law doesn't matter about little things."
The Parable simply means that great things have small beginnings and will meet opposition.