When I was little, I used to play with my friends by making mud balls from the nearby field and throwing them at each other.
ご質問ありがとうございます。
"When I was little, "＝「私が小さいとき」
"I used to play with my friends"＝「友達と遊んでいた」
"by making mud balls from the nearby field"＝「近くの畑で土団子を作り」
"and throwing them at each other."＝「そしてお互いに投げ合って。」
ご参考に。
アメリカ合衆国 
