Traditionally, there has been a lot of ghostly folklore associated with graveyards and cemeteries, mainly due to their close ties with the dead. While very little of it seems to carry any real substance as far as real-life ghostly encounters go, there is at least one curious case in the annals of psychical research which seemed to focus around an encounter with a spectral figure that reportedly occurred inside a church graveyard. This particular case is Case #29, found in the classic 1886 anthology Phantasms of the Living compiled by Edmund Gurney, Frederic Myers, and Frank Podmore [1, Vol I, pp. 212 - 214]. It did not relate to anyone who was actually buried in the graveyard at the time (and so it wasn't a haunt-related ghost in that traditional sense); rather, it seemed to be related to a widowed woman, known as Mrs. de Freville, who was said to have a particular interest in memorial structures (and one in particular, as we shall see). It thus seemed to be a fitting case to examine on the occasion of Memorial Day weekend.
The encounter took place on the evening of May 8, 1885, when a British gardener by the name of Alfred Bard was passing through a small church graveyard while on his way home from work. The account he gave of his experience went as follows:
On entering the churchyard...I looked straight at the square stone vault in which the late Mr. de Freville was at one time buried. I then saw Mrs. de Freville leaning on the rails, dressed much as I had usually seen her, in a coal-scuttle bonnet, black jacket with deep crape, and black dress. She was looking full at me. Her face was very white, much whiter than usual. I knew her well, having at one time been in her employ. I at once supposed that she had come, as she sometimes did, to the mausoleum in her own park, in order to have it opened and go in. I supposed that Mr. Wiles, the mason from Cambridge, was in the tomb doing something. I walked around the tomb looking carefully at it, in order to see if the [mausoleum] gate was open, keeping my eye on her and never more than five or six yards from her. Her face turned and followed me. I passed between the church and the tomb (there are about four yards between the two), and peered forward to see whether the tomb was open, as she hid the part of the tomb which opened. I slightly stumbled on a hassock of grass, and looked at my feet for a moment only. When I looked up, she was gone. She could not possibly have got out of the churchyard, as in order to reach any of the exits she must have passed me. So I took for granted that she had quickly gone into the tomb. I went up to the door, which I expected to find open, but to my surprise, it was shut and had not been opened, as there was no key in the lock. I rather hoped to have a look into the tomb myself, so I went back again and shook the gate to make sure, but there was no sign of any one's having been there. I was then much startled and looked at the clock, which marked 9:20. When I got home I half thought it must have been my fancy, but I told my wife that I had seen Mrs. de Freville.
Mr. Bard's wife confirmed that her husband had indeed told her about the encounter, noting that:
When Mr. Bard came home he said, "I have seen Mrs. de Freville tonight, leaning with her elbow on the palisade, looking at me. I turned again to look at her and she was gone. She had [a] cloak and bonnet on." He got home as usual between 9 and 10; it was one the 8th of May, 1885.
Later on it was learned that Mrs. de Freville had actually died on that very day, about seven hours before Mr. Bard had seen her in spectral form . This particular case would generally fall under the classification of a crisis apparition, where the spectral figure of a particular person is seen in fairly close proximity (usually 24 hours or less) to the time when that person experienced a moment of crisis (in this case, death). What is particularly interesting here is that at the time he saw her, Mr. Bard was unaware that Mrs. Freville had died earlier that day - he only found out about it the day after.
Assuming that it indeed took place exactly as recounted, what might've been involved in this particular encounter? It's hard to know for sure, but apart from entertaining the idea of a spontaneous spectral appearance on the part of the deceased Mrs. de Freville, one might also consider the possibility that Mr. Bard's experience was facilitated through a subtle retrocognitive (i.e., psychic perception of the past) impression relating to Mrs. de Freville's passing earlier in the day. In the latter situation, if the initial sight of the mausoleum had momentarily turned Mr. Bard's thoughts toward Mrs. de Freville in any way, perhaps that might've helped facilitate a psychic impression relating to her, which Mr. Bard experienced in the form of a fleeting apparition. This would be based on the idea that memory plays a role in ESP, as some research findings seem to suggest [e.g., 3-7]. A possible hint in this direction comes from Mr. Bard's note that the figure he saw of Mrs. de Freville was "...dressed much as I had usually seen her," which is in line with the observation made by parapsychologist Richard Broughton that "the clothing that the ghost appeared in was what the deceased customarily wore, not necessarily those in which the person died" [7, p. 150]. This may be one thing which suggests that some apparitional experiences draw upon the witness' own memory of the person seen in order to facilitate the representation of that person in spectral form.
In discussing this case, Gurney and Myers [8 - 9] had both drawn attention as well to the specific locale (the mausoleum) where Mrs. de Freville's apparition was seen, since it seemed to carry some significance to her (given that she was known to visit it from time-to-time). Through her repeated visits, might it have gradually built up and retained some form of localized "place memory" that helped trigger Mr. Bard's experience? Such an idea would be based on physician and parapsychologist Pamela Heath's suggestion that perhaps some "place memories" may be formed through repetitive action [10, p. 75], coupled with a spontaneous form of psychokinesis (PK, or "mind over matter"), a suggestion which seems to receive some preliminary support from certain studies involving apparent PK "linger" effects.  Perhaps to that extent, a kind of "haunt"-related effect could've been involved here.
All of these ideas currently remain speculative at this point, and are simply offered here as possible "food for thought." Whatever the situation, this "memorial ghost" case seems to be a rather intriguing one to ponder.
The PRF would like to wish everyone a safe and peaceful Memorial Day weekend.
References & Notes:
 Gurney, E., Myers, F. W. H., & Podmore, F. (1886). Phantasms of the Living [2 vols.]. London: Trubner & Company.
 It turns out that the approximate time of Mrs. de Freville's death as originally listed in the Phantasms entry was erroneous - she had died around 2 P.M., rather than at 7:30 P.M. as listed in the entry. This is based on a correction later given on page 415 of Gurney, E., & Myers, F. W. H. (1888-89). On apparitions occurring soon after death. Proceedings of the Society for Psychical Research, 5, 403 - 485.
 Roll, W. G. (1966). ESP and memory. International Journal of Neuropsychiatry, 2, 505 - 521.
 Irwin, H. J. (1979). Psi and the Mind: An Information Processing Approach. Metuchen, NJ:Scarecrow Press.
 Palmer, J. (2006). Memory and ESP - A review of the experimental literature. European Journal of Parapsychology, 21, 95 - 121.
 Stanford, R. G. (2006). Making sense of the "extrasensory" - Modeling receptive psi using memory-related concepts. European Journal of Parapsychology, 21, 122 - 147.
 Broughton, R. S. (2006). Why do ghosts wear clothes? Examining the role of memory and emotion in anomalous experiences. European Journal of Parapsychology, 21, 148 - 165.
 See pages 268 & 301 - 302 of Volume II of Reference 1.
 See page 416 of the article cited in Note 2.
 Heath, P. R. (2004). The possible role of psychokinesis in place memory. Australian Journal of Parapsychology, 4, 63 - 80.
 Williams, B. J., & Roll, W. G. (2006). Psi, place memory, & laboratory space. Proceedings of Presented Papers: The Parapsychological Association 49th Annual Convention (pp. 248 - 258). Columbus, OH: Parapsychological Association, Inc.