[D] MNIST equivalent dataset for RNN/LSTM/Transformer?

Hi, I'm developing a course material and looking for a nice introductory task/dataset for RNN/LSTM/Transformers. I can use recurrent networks for MNIST too, but I'm looking for a more "classic" example such as sequence prediction or classification. Is there any? Preferably it's relatively simple, clean and well-known dataset like MNIST. Thank you very much.

dataset lstm machinelearning mnist rnn transformer