I don't really think of it as collecting- but I guess it's owning multiples. So I have:
classic cars- we have 3, my avatar is the newest 67 Firebird, oldest is my 57 Metropolitan, hubby has a 65 Corvette Stingray
tea pot collection (I even have one that is a sewing machine)
crystal- Many many pieces- I have service for 18 for our family that we use every holiday. I don't believe in saving it "for good"- I use all of it.
Some pieces of Fenton and Carnival glass.
Metropolitan items (my 1957 car)- I love my cookie car
lots of sewing "stuff" tubs of fabric and 8 machines and notions.... I know you can relate to this part-and no- it's not hoarding, it;s kept nice and neat.
I started collecting old cook books, my favorite, which I use is a 1942 Good Housekeeping with a war supplement on how to use rations and cook without various items.
Hubby collects mining memoribilia- mostly the anthracite coal stuff (we are in that region) and accordians- he has 5.
my house is nicely cluttered but not messy. I have one room- the formal living room that we display a lot of the items that no one goes in. But I live in my sewing room- my favorite room in the house.