Here's a compound sentence joined by the conjunction "and":
"I went to the store to buy groceries, and I also stopped by the post office to mail a package."
In this sentence, two independent clauses are connected by the coordinating conjunction "and." The first clause is "I went to the store to buy groceries," and the second clause is "I also stopped by the post office to mail a package." The conjunction "and" combines these two related ideas into a single compound sentence.