Can a sentence start with a word “each”
For example, Each column was filled with pebbles.
Yes. “Each” is what we call a “singular indefinite pronoun.” Other such pronouns are:
You can start a sentence with any of these:
Each of the students was prepared.
Any of the students could solve this problem.
Much depends on your success.
I'll try to post a longer item soon on indefinite pronouns. They can pose a lot of problems.