Examples could include resource plants such as:

Blaze Plant, when broken drops resource worth 1/4th of a blaze powder. Potentially configurable to instead drop a full blaze powder. Maybe sets you on fire if you punch it with a fist.

Magma Cream plant, which would probably function the same as the Blaze Plant?

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Or they could include food plants, such as:

Glistering melons, melons that drop glistering melon slices instead. Might have some caveat to its growth to balance it?

Some sort of firefruit, which would need additional processing to not set the player on fire. Maybe craft it with a snowball?

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These are some general ideas to remind you about this, as you requested.