In the sentence "The flock of sheep scurry down the path, nudged on by the border collies running beside them," the subject "flock" does not agree with the verb "scurry" because "flock" is a collective noun and is considered singular. The correct form would be "The flock of sheep scurries down the path...".
If you are looking for a sentence where the subject agrees with the verb, you would need to rephrase it as "The flock of sheep scurries down the path...".