This chain quest gives 10200 xp.

Quest starts at Dalson's Tears.
Go inside Barn and click Diary on floor to start quest.
Kill Wandering Skeleton outside the barn, loot Dalsons Outhouse Key (lootable by all in group)
Use key on outhouse (48,49ish)
Kill Farmer Dalson, loot Dalson Cabinet Key.
Go inside house, 2nd floor open cabinet.
Rewards:
7050 xp,
Farmer Dalson's Shotgun,
Dalson Family Wedding Ring
and, we had a chest spawn out of the cabinet that had Axe of Rin'ji in it

Edited, Thu May 12 15:44:45 2005

Well this quest appears bugged... Wandering Skeleton does not spawn, so it's impossible to get the Outhouse Key

Do as Badfish says and you'll gain 10,200 xp as of 2.3

Quest bugged for me now, one week ago it worked. Here's the differences:

A week ago: I entered the big building first and clicked the cabinet. As nothing happened I checked here on wowhead what to do, went to the barn, clicked diary. Went to back of barn, killed Wandering Skeleton, used outhouse, killed mob, to cabinet and all fine.

This time: I entered barn first, while clearing the last two mobs the Wandering Skeleton spawn on me. I kill him before clicking the diary, then I wait for a repop. Scarlet humanoids attack him, I go all out nuke on him while he's at 92%, I take him down almost full but no loot for me. Waiting for repop, he spawn, I kill him and get key. Now I can't interact with the outhouse, just like people described here.

I'll send a GM ticket right away with the exact same info I wrote here. Assuming you are not allowed to hit the Wandering Skeleton before you used the diary?

Edit; GM replied just 10 mins after petition. Here's part of the dialogue:
GM: We are aware of this issue yada yada.
me: ok thanks. Hope the information I provided can help solve the quest (as I noticed a difference from where it work/doesn't work).
GM: Yes this also seems to happen if Farmer Dalson is killed too far away from the outhouse.
etc..

All in all; if what the GM says and my own recent experience from two alts is correct, this quest will work if you don't kill Wandering Skeleton before you have used the diary, and if you kill Farmer Dalson next to the outhouse.

This particular strategy would work for rogues only. Outside the barn, get the attention of the Scarlets, run inside the barn to the diary (getting the attention of the ghouls), vanish. The Scarlets and the Ghouls will fight it out and you get a ringside seat. The Scarlets win and leave to patrol outside again. Read the diary at your leisure.

Keeping the Scarlet units cleared allows you to see the Wandering Skeleton patrolling in and out of the building. It seems the Scarlet units were placed there to take out the Wandering Skeleton, just as with the Gibbering Ghoul and that set of Scarlet units in the Felstone Field.

After I did the quest with the diary, I saw a note in my log: "Mrs. Dalson' Diary" -- completed. I was a little confused but the skeleton will wander INTO the barn after about 4-5 minutes, if you want to just wait there. I would say it was about five minutes. The key dropped from the skeleton and I proceeded to open the outhouse. Killed old Farmer Dalson, waited for the disease to wear off (so I could stealth) and went up to the cabinet. Wallah!

For those of u wondering of the exp, u will get awarded at the end of the chain (10200xp)

The quest seems to be fixed now, or at least it wasn't bugged for me just now.

In case it is still bugged, and I just happened to get lucky and do it the "right" way, I'll do my best to describe exactly what happened. I read the diary after killing off all of the mobs inside of there, and then I went outside and killed the group of scarlet mobs because I accidentally aggro'd them. A few moments after I had killed them, the wandering skeleton aggro'd to me while I was drinking a few steps out the door to the barn. I killed, him, looted the key and started to make my way to the outhouse. I got feared into a ton of mobs so I ended up running far past the outhouse to drop aggro and heal up. Afterward, I walked up, right clicked the outhouse, went through a complete quest window, and then the farmer spawned on top of me.