あつめた translation

Hello,

Please help me with 「あつめた」 in the following sentence:

とのさまの まえで あつめた はいを まきましたが
はなが さくどころか とのさまは はいだらけ。

Maybe I can translate it as

(He) scattered collected ashes in front of the land lord but,
instead of flowers blossom the land lord was covered with ashes.

Yet, I am not sure if my translation correct. あつめた is past form for verb あつめる.
But in my translation あつめた sounds more like adjective.

Thank you very much!

You're right -- it is the past form of あつめる. Verbs can modify nouns directly in Japanese, so it means "the ashes he collected". Check this out: Relative clauses.

Thank you so much for your kind help!