The Wikipedia page on adjuncts gives the example
Yesterday, Lorna saw the dog in the garden.
Notice that this example is ambiguous between whether the adjunct in the garden modifies the verb saw (in which case it is Lorna who saw the dog while she was in the garden) or the noun phrase the dog (in which case it is the dog who is in the garden). The definition can be extended to include adjuncts that modify nouns or other parts of speech (see noun adjunct).
The page on noun adjunct says (emphasis mine)
a noun adjunct ... is an optional noun that modifies another noun
Seems to be only about using nouns like adjectives, so actually "in the garden" doesn't seem to be a noun adjunct at all.
Can adjuncts ever modify nouns? What is the correct term for the parallel to adjuncts regarding nouns/noun phrases? E.g. could "on the plate" in
The sauce on the plate was eaten by him
Have any name in addition to prepositional phrase?