I found Hanafuda FAQs in English, but no Illya's Castle FAQs which can be a bit frustrating if you're going for 100% item completion.
Translated from
here, to hopefully make things less frustrating for the people who are catching up:
Illya's Castle - Item FAQ
First row:
Caliburn: Dropped by defeated enemy Servants. Your Master can't be Shirou.
Tohsaka's pendant: Dropped by defeated enemy Servants. Your Master can't be Rin.
Book of False Attendant: Dropped by defeated enemy Servants. Your Master can't be Sakura.
Holy Grail: Rare chest spawn. Only found in Die Lorelei stage.
Japunika Assassination Note: Uncommon chest spawn. Only found in Die Lorelei stage.
Second row:
Saber's stuffed toy: Dropped by defeated enemy Saber.
Saber's rice bowl: Random chest spawn. Your Servant must be Saber.
Rider's glasses: Random chest spawn. Your Servant must be Rider.
Caster's coin: Dropped by defeated enemy Caster.
Caster's ring: Random chest spawn. Your Servant must be Caster.
Third row:
Excalibur...?: Dropped by Gilgamesh.
Golden earrings: Dropped by Gilgamesh.
Lancer's fishing rod: Dropped by defeated enemy Lancer.
Archer's slippers: Dropped by defeated enemy Archer.
Archer's ladle: Random chest spawn. Your Servant must be Archer.
Fourth row:
Tiger strap: Common chest spawn.
Maid uniform: Common chest spawn. Only found in Die Lorelei stage.
Hanging scroll: Common chest spawn.
Beef 2000: Common chest spawn.
A spoon from Taizan: Common chest spawn.
Strategy:
The best way to collect all items is to grind the Big Bridge stage with several Servant/Master combinations using the Scene Select feature.
That stage has many random chests, and it's easy to pick on enemy Servants because they will have a very hard time getting past Gilgamesh unless you kill him yourself.
Once you have everything but the Die Lorelei exclusive items, start grinding that stage until you get the missing items, especially the elusive Holy Grail.
Don't worry about finishing the stage; even if you die/finish last/time runs out, the found items will be recorded. In Die Lorelei stage in particular, it's best to let the time run since random chests will pop up every now and then.
You can include this in any FAQ/walkthrough/readme/stone tablet of your liking. No need to credit.