At one time or another, you'll usually end up with an excess of almost any item. Usually it's due to a quest forcing you to adventure in one place many times, but there are lots of reasons why you'd wind up with an abundance of one item.
One of your options, naturally, is to simply throw away the excess of that item when your inventory gets too full. And if you're in a hurry to make space (say for a ridiculous Liang request), then that may be the best option.
Another option, naturally, would be to sell the excess in the Sea Trading market. However, if this is for a seasonal quest, then it's likely that everyone else has the same idea, so the item will just wind up sitting on your boat for four hours (two selling cycles) and taking up space there.
So generally, your best (and most profitable) option is to make other things that people are likely to need, and sell those, either in the market or, if possible, to Myra.
So with this in mind, I'm starting this occasional series to help you know which items are the most profitable and fast to make with an excess of a given ingredient. Of course, you can always just check the ingredient page itself on this site as well; every one of those has a complete list of items which can be made with that ingredient. But those lists don't include information about how long they take to craft, how much they'll net you in the market, etc.
I hope this series helps you, and if you have any suggestions or questions, feel free as always to contact me either via my Facebook page (link at top left) or at the email address on the Welcome Page. Happy crafting!