C# - Multiple groupings

Question

I have an IList<SomeObject> where SomeObject has properties for Date (DateTime) and SomeEnum. I've been trying, first with extension functions then with for loops to group first day, they by the value of the enum. I need the output as SomeObjectGroup objects, where the groups have properties for Date, the enum value and a List<SOmeObject> of things on that day.

The final variable needs a signature of IDictionary<DateTime, IList<SomeObjectGroup>> (the time part of DateTime isn't used), but I'm tearing my hair out with this. Nested loops always get complicated quickly which is why I wanted to use lambda functions, but I just need ot to work (albeit if in a series of steps).

So to clarify (in as simpler sense possible): From IList<SomeObject> to:

IDictionary<DateTime, IList<SomeObjectGroup>> x = {
  "2009-10-10", enumGroups = {
      SomeObjectGroupA {
        Date = "2009-10-10", 
        TheType = BlahEnum.TheFirst,
        Items = {
          SomeObject1,
          SomeObject2,
          ...,
        },
      SomeObjectGroupB {
        Date = "2009-10-10", 
        TheType = BlahEnum.TheSecond,
        Items = {
          SomeObject3,
          SomeObject4,
          ...,
        },
        ... group for the rest of the enum values (if present on this day of the original list)
      "2009-10-11", enumGroups = {
      SomeObjectGroupA {
        Date = "2009-10-11", 
        TheType = BlahEnum.TheFirst,
        Items = {
          SomeObject5,
          SomeObject6,
          ...,
        },
      SomeObjectGroupB {
        Date = "2009-10-11", 
        TheType = BlahEnum.TheSecond,
        Items = {
          SomeObject7,
          SomeObject8,
          ...,
        },
  }

Anyone fancy a stab?

}