The story that it comes from the song  Green Grow the Lilacs,  said to have been sung at San Jacinto, is an example of folk etymology.
( ( ( The story ) ( that ( it ( ( comes ( from ( the ( song ( Green Grow ) ) ) ) ) ( ( ( ( the Lilacs ) , ) ( said ( to ( have ( been ( sung ( at ( San Jacinto ) ) ) ) ) ) ) ) , ) ) ) ) ) ( ( is ( ( an example ) ( of ( folk etymology ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN story)) (SBAR (IN that) (S (NP (PRP it)) (VP (VBZ comes) (PP (IN from) (NP (DT the) (NN song) (NNP Green) (NNP Grow))) (NP (NP (DT the) (NNPS Lilacs)) (, ,) (VP (VBN said) (S (VP (TO to) (VP (VB have) (VP (VBN been) (VP (VBN sung) (PP (IN at) (NP (NNP San) (NNP Jacinto))))))))) (, ,)))))) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (NN folk) (NN etymology))))) (. .)))
An example of folk etymology is that song
( ( ( An example ) ( of ( folk etymology ) ) ) ( is ( that song ) ) )
(ROOT (S (NP (NP (DT An) (NN example)) (PP (IN of) (NP (NN folk) (NN etymology)))) (VP (VBZ is) (NP (DT that) (NN song)))))