What is the Latin for
" John and Lucille made me. 1999."
Where "me" is a garden. To be inscribed on a stone.

Hello.

I'd go with:

"Ioannes et Lucilla me fecerunt. MCMXCIX."


Breaking it down:

John = Ioannes
http://freereg.rootsweb.com/howto/latinnames.htm

Lucille = Lucilla
http://www.behindthename.com/nmc/rom-anci.html

"me fecerunt" = "they made me"

Examples of similar usage:

'The bell is inscribed as follows : ?MDCCX1111 Claes Noorden et Jan
Albert de Grave me Fecerunt Amstellodami?, which means: "Klaas Noorden
and Jan Albert de Grave made me in Amsterdam in 1714".'
http://www.strooidak.co.za/klok&begrafplaas_engels.asp

"Me Fecerunt Fratres Paccard Ad Annectum (The Brothers Paccard made me
for the purpose of convocating)."
http://www.geocities.com/Heartland/Meadows/2700/story65.htm

On an antique organ made by brothers named Ricci:
" Fratres Ricci de Verruculo me fecerunt A.D. MDCCLXXXV" 
http://www.organisti.it/concerti_sangiov_marignano.htm

1999 = MCMXCIX
://www.google.com/search?hl=en&q=MCMXCIX&btnG=Google+Search

----------
search strategy:
my own knowledge of Latin, plus various searches:
lucilla latin
ioannes latin
"me fecerunt"

I hope this helps.

I feel that juggler-ga's answer is excellent, though I think some
people would prefer:
"Hic Hortus Feceruntur a Ioanne et Lucilla."
This places the focus on the garden, as it uses the perfect passive
indicative, with the ablative of agent. The subject of the sentance is
now "This garden" rather than "John and Lucille".

This translates to:
"This garden was made by John and Lucille."