YOU SAID:

i was walking and tripped over a piece of a thread of yarn

INTO JAPANESE

私は歩いていて、糸の糸の上につまずいた

BACK INTO ENGLISH

I was walking and stumbled on a thread of thread

INTO JAPANESE

私は歩いていて、糸の糸につまずいた

BACK INTO ENGLISH

I was walking and stumbled upon a thread of thread

INTO JAPANESE

私は歩いていて、糸の糸につまずいた

BACK INTO ENGLISH

I was walking and stumbled upon a thread of thread