Edit: A huge thank you to everyone who helped me pick a theme! Tavore's TC is now happily carnival based! I've gotten together a huge chunk of things (on my wishlist here and here along with some already in his TC here if you want to poke around) but I could still use some help!
I've manged to find a TON of carnival-appropriate food, but food and balloons are the bulk of his wishlist right now. I could really use some help finding cheap looking plushies/toys/wearables that could be seen as carnival prices. And of course anything else carnival (or even circus/theme park) related that I might have missed!

Hmm, maybe a circus/carnival theme? Like
I'm sure there's more but I don't wanna go ham if you're not into it lol :)

a carnival pet sounds good! maybe they work on the high-wire or acrobatic stuff?
So many slots to fill! OwO I'm trying to think of themes that cover a wide range of items, although I'm a big fan of the carnival idea!
Perhaps you could create a character with a love for plushies, or someone who makes toys for children maybe? There are so many plushies and toys on-site to work with.
I like these ones:
You'd also have an endless supply to choose from if you gave him any kind of character that fit in with any of the Subeta Holidays. Zombie/Undead/Steampunk/Pirate/Wintery/etc There's always Earthy items in general instead of just flowers.
Other basic concepts you could expand on: Beach bum (sea shells, sands, surf boards, sunglasses). Healer or shaman (medical supplies, medicinal plants, crystals, potions, animal parts). Artist (brushes, prints, paints, craft materials, computer stuff) Merchant (baskets and food, cloth, jewelry, tableware, spices, lanterns, animal parts) Pawn/antique shop worker (guitars, jewelry, records, autographed stuff, furniture. Basically anything fancy-looking, including weapons) Carpenter or interior designer (furniture, tools, paints) Farmer (crop food, baskets, minions, soil) Baristsa (coffee, tea, hot chocolate, syrups) Mixologist (alcohol, shakers, lemons/limes/cherries, drink umbrellas, ice cubes) Animal sanctuary owner (minions/medical supplies)
I used to have a pet that lived in an antique shop and currently have one that works at a carnival- both were fun themes to work on. c:
I like filling big TCs with relatively themeless items, that fit a certain colour scheme or aesthetic? Like this one?.
As an alternative, you could take advantage of the scale of it, and do a really really long colour graduation? Make it go right down the page, full of random items but arranged in such a way? Either a full rainbow, or maybe just from one shade of pink/blue in his design to another? c:
(Also, hi! You almost certainly don't remember me, and I don't blame you, but we used to know each other on Chickensmoothie a couple of years ago! I was either Mills or Milliepops or Milliekinz on there, I can't exactly remember, but, yeah. We both used to hang around the character adoption threads. c:)

Thank you all so much for the ideas! :D I think I'm going to go with a carnival theme for Tavore since it really seems to fit the Sweetheart Aeanoid (plus its a super cute idea). I'm definitely gonna keep that theme list from Kestrel and use it for other TCs. Some of them look like they'd be so much fun for me!
I absolutely love TCs like that but I've never been able to pull them off myself (unless all the items fit a larger theme). Maybe one day I'll work up the motivation to try it because that gradient plushie TC I did was a lot of fun.
(Oh my gosh hello! I do remember you! :D I've still got the art you did for me, and I still love it.)
Never noticed that you changed the title until now, but I thought I'd throw some ideas at you in case you're still looking! They'll be a mix of carnival/circus/sideshow since they're paired up pretty often. You could also throw in a county fair theme if you wanted by including large produce, the blue ribbon food, livestock, etc.
Circus animals: [item=Mr. Giggles] Basically any poodle or small dog, especially ones that are dressed up or look dyed.
Prize fish:
General rides/games/carnival As well as any oversized plushies, cheap-looking toys, tributes to cartoons, posters, etc. You can always check the toy and carnival shops or carnival game prizes for more ideas.
Sideshow: Could also use different zombie items or basically any other minions that are mythological or obvious crosses between two animals or have more appendages than the norm. Masks work too since a lot of sideshow attractions were intentionally misleading if not outright lies.
IDK IF ANY OF THESE WOULD INTEREST YOU FOR CASTELIA OR IF YOU'D WANT TO PITCH SUGGESTIONS BUT