I'm slowly starting to gather up codes for some of the stuff that cant be bought in buydebug.

Base Game Garden Plants
Apple: 0x000055B3
Basil: 0x0000B2A4
Blue Bells: 0x00005B9D
Carrot: 0x0000B0F3
Chrysanthemum: 0x00005B9B
Daisy: 0x00005B99
Grapes: 0x00005B92
Lemon: 0x000057C2
Mushroom: 0x0000B0FF
Parsley: 0x0000B2A6
Plantain: 0x000057C4
Sage: 0x0000B2A8
Snapdragon: 0x000055A6
Spinach: 0x0000B961
Cherry: 0x000057C3
Lily: 0x00005B9A
Onion: 0x0000B53C
Pear: 0x00005B95
Potato: 0x0000B0EF
Rose: 0x00005B97
Strawberry: 0x00005B8D
Tomato: 0x0000B500
Tulip: 0x00005B98
Bird of Paradise: 0x00005B9F
Blackberry: 0x00005B8E
Bonsai Bush: 0x0000B2C7
Cow Berry: 0x000093E2
DragonFruit: 0x00005B90
Orchid: 0x00005B9C
Pomegranate: 0x00005B8F
Trash Fruit: 0x00005FAE
U.F.O: 0x00007151

Outdoor Retreat Garden Plants
Chamomile: 0x0001025F
Toxic Chamomile: 0x0001071C
Elderberry: 0x0001025C
Noxious Elderberry: 0x00010723
Huckleberry: 0x000107E4
Muckleberry: 0x000107E5
Fireleaf: 0x000102A0
Poison Fireleaf: 0x00010725
Morel Mushroom: 0x00010261
False Morel Mushroom: 0x00010724

what I'm missing so far...

Death Flower

Anyone have an idea of how to find it?

found these in the object folder of the XML for the game:
0x0000000000018F9F
0x0000000000018F9D

Not really sure what you mean that they can't be bought in the buydebug, because that's where I get them all the time. The problem is that they don't show up before you type the item you need into the search bar. For instance, if you type in Death Flower in the search bar, that's when you get to see it... plus all the other fruits and vegetables in the game (and many more items).

Other than that great work on this list. It's definitely useful!