Below are the possible rewards you could receive (shipping including!) from ordering a $12 Small McNuggies Meal on this page : My Stream Elements Tip Page 
Under the list of rewards are the rest of the pictures of possible items, sorry if it's a little clunky! You can also check the status of any item (if it's been pulled yet) and sort by rarity for the most up to date info on the probability of getting your target or a high rarity item! 
Since I haven't finished the item descriptions on this page yet, for a quick definition, a "mystery" item will be picked from existing things I have made, best trying to honor any requests you have, and job stones, you can pick the job. For "Surprise" items, its a semi-custom new item - you can pick a color and give me a couple details, but it will be a 'surprise' according to your short request. For "Custom" items, I'll work with you to design the item according to your ideas. The full terms will match the 'custom' items I offer in my shop currently, and this page will be updated with the full description very soon! 

Best of luck!