Which spells count for a Shepherd Druid’s features affecting creatures “summoned or created” by spells?

I was looking at making a Circle of the Shepherd Druid for a game and noticed a part of the Mighty Summoner and Guardian Spirit features regarding creatures “summoned or created” by spells. For instance, the Mighty Summoner feature says (XGtE, p. 24):

Any beast or fey summoned or created by a spell that you cast gains the following benefits:

(The corresponding part of the Guardian Spirit feature is worded differently, but is essentially identical.)

My first instinct was “oh, so conjure animals“, but then I would like to have more than one spell to be the beneficiary of two of my subclass features. So, which spells count for these two Shepherd Druid features?