sagas.js

...
function* pollSagaWorker(dataKey) {
  while (true) {
    const contracts = yield select(getContracts);
    if (contracts.SimpleStorage.synced) {
      const storedValueObj = contracts.SimpleStorage.storedData_[dataKey];
      if (storedValueObj && storedValueObj.value) {
          yield put({ type: 'GOT_STORED_VALUE', storedValue: storedValueObj.value });
      }
    }
    yield call(delay, 200);
  }
}

function* getStoredValueWatcher() {
  while (true) {
    yield take('GET_STORED_VALUE');
    yield put({ type: 'GETTING_STORED_VALUE' });
    const drizzle = yield select(getDrizzle);
    const dataKey = drizzle.contracts.SimpleStorage.methods.storedData_.cacheCall();
    yield race([
      call(pollSagaWorker, dataKey),
      take('GOT_STORED_VALUE')
    ])
  }
}

export default function* root() {
...
  yield getStoredValueWatcher();
}