I bet you're wondering what an "object" is. Well, for all intents and purposes, an object is anything in Sweet Home that can be interacted with that doesn't hurt you, block your path, or impede your progress in any way (excluding items, weapons, and uh...people I guess). For things that for whatever reason affect your party negatively, check the Obstacles Section.
Dock -Places where you can moor the rowboat on the lake.
Hole -Basically an open door, but caused by a different event (generally revealing a secret passage).
Opened Door -Open a locked door, and this is left behind. I'm sure you all know how to go through an open door...
Pegs -A rope ladder can be used at these two pegs to reach a new area.
Plank -If one of your characters happens to get caught in a sand trap in the dungeon, have someone stand on a plank and USE a Rope to save the character in the sand trap.
Post -Use a rope or a bow to cross gaps that have a post on the other side.
Canoe -Find this on the lake, dock it at the docks to reach new areas and islands. Only two party members fit at a time.
Cart -This is found in a hallway in the Basement. Only two party members fit in it at a time. Pretty pointless. You can go back and forth along a track, but you can't get anything accomplished...has anybody found a use for this?
Blood Notes -Look at these two receive hints as well as background information on past experiences in the mansion.
Bulletins -Notes posted on the wall. Look at them to gain info.
Diary -After getting the Diary key, the Diary can be read. Later in the game, it's no longer an object, but instead, an item.
Dolls -Look at these and they might give you a hint (only three in the game do, and their hints are all, for the most part, useless).
Frescoes -Look at these, clean them if they're dirty (use the Broom or Vacuum), and use the Camera on them for helpful hints or information on Lady Mamiya's past.
Notes -Very common. Read these and you'll get a helpful hint.
Skeletons -If you look at the skeletons you find around the mansion, some of them will give you hints.
Weird clue-giving guys -I don't know what these things are, but talk to them and they'll give you a clue.
Zombies -Don't be afraid, just talk to the zombie and they'll give you helpful, if not cryptic, information.
Cats -There is no reason for these to be in the game. If you Look at them, it'll just say "A silent cat", or something to that effect. I don't know why they bothered programming this into the game...
Mice -Just like cats, pretty useless. However, one mouse on the second floor helps you to find the Mallet (sort of...).
Generator -Use the Gas on the Generator and turn it on, and you'll be able to proceed to the Northern Region.