One thing that is always needed by a group and by the Kingdom itself is the shiny stuff that is handed out with awards. This includes scrolls, AoA and GoA bands, and the individual regalia piece that any given award might have along with it. Those goodies have to come from somewhere! Now you can't exactly just walk into Hobby Lobby and pick up hand painted and written scrolls, can you! Those amazingly gorgeous pieces of work are hand-crafted by craftsmen in our own organization. The calligraphy writing and the illumination artwork are just a few of the fun activities within the SCA that some choose to do, and this is one outlet where their goods can go to service their group and/or the Kingdom.
You can read more about regalia and the bagatelle -- which is the group who takes up offerings of regalia for the Crowns -- on the Regalia page.
http://bagatelle.meridies.org/regalia/?page_id=57
The Crowns can also be supplied with Largess. This can include small tokens that they can give away to the populace, to their entourage, or to whomever they please. Whenever you pick up an interest, you can make individual things suitable for this purpose. When the Barony/group or guild you're with decides to offer up a gift basket during a presentation court, you can donate the items to that basket! For example, I am in the Herbal guild, and sometimes I will put together things such as lip balms or skin salves, a pouch with different dried herbs a cook might enjoy, or small herbal sachets. I was presented with a drop spindle during the middle of an event by His Royal Majesty because he observed me participating in the craft of weaving. I was totally floored. So you see, a thing that may be small for a woodworker to put together, may mean so much and truly encourage an artisan when they receive it. Just present your best work and if it's something you think others would like to get for whatever reason, go for it!
See also, What is Regalia