There are grammatical problems in those sentences.
1) 洗うと思っていた sounds like the subject is not the speaker. The volitional form is better.
2) ジャガイモに見つかる means that the subject is found by potatoes.
3) Semantically, an adversative conjunction is more appropriate to connect the two sentences, not そして.
As for the repetition, you can use a pronoun like の, but I don't think it's not so bad to use ジャガイモ twice.