Perry,
As cofty explains, these people didn't necessarily all lie, they may very well have truly believed Jesus rose from the dead.
Strong emotions can make people 'experience' weird things.
Strong beliefs can make people 'experience' weird things as well.
Combine the two, and quite strange stories may result.
Could it be that the women actually saw the gardener, not a ressurected Jesus? Could it be that the gardener decided to play along a little bit, for whatever reason (maybe simply to comfort those women)? Could it be that the other disciples were so much influenced by the words of the women and their own emotions and desires that they too perceived the gardener as being a ressurected Jesus? Could it be that the gardener took off once things went too far, and the his disappearence became a mythical ascension when the stories were written down decades later?
It's all quite plausible. To me more so than someone being raised from the death.
Countless other events might also explain the stories.
People are known to be highly susceptible to suggestion and delusion.
(Some very nice examples can be found here: https://en.wikipedia.org/wiki/Mass_hysteria )
Regardless, the stories about all this were written decades after the alleged facts, by people who by then had a belief system completely depending on the story being true. They might have added some elements here and there. Just a tiny claim about how many people witnessed an event. Just a tiny anecdote about Jesus entering a locked room or showing his stigmata. Just a story about angel Moroni and his golden plates. Just a story about seeing a cross and In Hoc Signo Vinces in the sky.
All that is not unheard of. People are known to sincerely misremember events that happened long ago. They are known to embellish stories about their country, their religion, their leader.
What is really the difference between some of the extraordinary claims collected in the Bible, and similar extraordinary claims made by others?
Why believe one, not the others?