「じつは自由研究で相談したいことがあって・・・」「どれ・・・。ふーん、被子植物について調べてるのね」

「・・・」「・・・。、」

'Actually, there's something I'd like to ask about for my independent research project...' 'Let's see... Hm, you're looking into angiosperms.'

Literal

'Actually, independent-research [about-で] want-to-consult thing [subject-が] exist...' 'Let-me-see... Hmm, angiosperms [about-について] researching [confirmation-のね]'

自由研究 is a standard Japanese school assignment where students choose their own topic — a fixture of summer homework. 被子植物 'angiosperms' is a biology term. どれ as an interjection means 'let me see,' distinct from the interrogative どれ 'which one.' The trailing ・・・ after あって signals hesitation — the student is nervous about asking.