有關英文grammar&sentence structure

lie + buried + deep

The format:
verb + adjective + adverb

lie (linking verb) 呈...狀態 = to be in a particular state or condition
e.g. The book lies open on the table. ("lie" is linking verb; "open" is an adjective)

buried (埋入的) = past participle of the verb “bury”. It is used as an adjective (bury-buried-buried)

e.g. If something lies forgotten, it has been and remains forgotten.
(forget-forgot-forgotten)
forgotten is a past participle used as an adjective

If something lies buried, it has been and remains buried.

deep (深入地) = adverb
deep can be used as an adjective, an adverb or a noun
e.g. The miners were buried deep in the ground.
("deep" is an adverb, not an adjective, were buried = main verb, in passive voice)

這三個字在你的句子很特別:

lie 不是 intransitive verb, 不是解 “躺著,說謊,位於”, 是 linking verb
buried 不是 main verb, (past tense of bury or past participle in passive voice), 是 past participle 用作 adjective
deep 不是 adjective or noun, 是 adverb. [deeply 也是 adverb.]

linking verb 是用來 link subject and complement.
She is a teacher. (is ~ linking verb, teacher ~noun)
She seems happy. (seems ~ linking verb, happy ~ adjective)

Linking verb 後面多數是 noun, noun phrase, noun clause 或 adjective

有些動詞如：sit, stand, lie, fall，其後可以用形容詞性質的補語（complement)，如：

The valley lay quiet and peaceful in the sun.
山谷在陽光下顯得十分寧靜。

She sat motionless.她坐著動也不動。

She fell unconscious on the floor. 她倒在地上，不省人事。

同樣道理...all kinds of things that lie buried deep in my heart.

的buried deep in my heart.也是形容詞性質的補語，用來修飾子句的主詞that即things

(that) (lie) (buried deep in my heart.)的結構，你大可看成為noun+verb+complement

希望幫到你！

Adverb is a word that adds more information about place,time,manner,cause or degree to a verb,an adjective,a phrase or another adverb:-In the sentence:-
bring out---verb
that were lain;
that were buried;
are adverb cl of cause.
The verb "lie deep" informal from lay,lain means try to reveal attention from yourself by write.