I had a player spring a sudden need for a creo or corpus vis hunt on me. Thoughts?
How about a pregnant mother womb (for Creo and even Corpus for hardcore player) 
Well... ahemn 
sperm would be a possibility. Had to be mythic of course.
While we are at it, what of an ancient fallos? Monolithic or Romano-Greek. And old temple for Bacchus perhaps.
"Fallos?" Is that an alternate spelling of "phallus?" Or a term I'm unfamiliar with?
The characters are currently in Northern Italy, so a Greco-Roman fertility statue is definately feasible.... And quite, well, gross. It might be amusingly fittting for the group I'm playing with this weekend.... How "historically mythic" is a fertility ritual around an ancient phallus, that produces CrCo Vis in the form of magical sperm?
... this might be a bit much. Any other thoughts? Or other concepts of fertility rituals?
It is the ancient Greek version of the word, but in fact I just simply misspelled it in Danish instead of in English - which is coincidentally the same spelling as its Greek origins.
I think it has a mythical feel so I wouldn't pause except to consider how your troupe might react to it..
My thought goes toward quasi-Christian rituals partly of blessing the fields with prayer and frankincense to calling on the Saints or even surviving pagan rituals of a maried couple copulating on the village field to ensure fertility.
Another possibility, if you have Ancient Magic, is to use the fertility fetishes from the chapter on ancient fertility cults. The can be harvested as appropriate vis. And if you ever plan to introduce the fertility magic they'd both awe and rant at their past ignorant use of the fetisches. Even if not planning to use it directly, you could always have some NPC pop by their covenant some day to ask them a few questions... In any case the fertility chapter is very thematic and fitting for this.
Other idea let's see...
An artist tools could contain some creo (let's say a painter brush, a sculptor tool or clay, etc.) or even a "work in progress" like an unfinished painting.
Someone great idea is mentem but is inspiration could well be Creo vis. Imagine a person who's a genius and generate (unknowingly) some Creo vis just before they get a famous idea. If the mage gather the vis, the person slowly loose it's inspiration (you could have a nice story hook if that genius is in fact another covenant vis source or even a magus hidden personnal vis source! or even a demon inspired artist).
I always tought that form vis is easier to find than the technique. Corpus= large quantitity of meat/body/blood (preferably with some signification). Perhaps some healer blood stained cloth, a miraculously healed warrior's bandage, etc.
Furion: I just picked up Ancient Magic over the weekend, but haven't cracked it yet. I"ll take a peek tonight.
Bellysarius: I like the artist's tool idea. Could lead to an interesting story... trying to bargain with / steal from a pious painter of churches, who's brushes are blessed with holy creo vis. Or maybe the pigment he uses is ground from a magical source.
Thanks fellas, keep em' comin'! The player needs 15 pawns, and fast!
I've always thought of Creo sources also being perfect examples of things, since Crea will always improve. Which makes Michalangelo's 'David' seem like a good source of both Creo and Corpus...... if only it hadn't been made in 1504.
I really like the creative sources as well.
But I'm afraid my next suggestions are still less savory.
Dung. It is used as a fertelizer, hence the Creo. Whether human mythic dung would be creo, well...
Scarab bettles. In terms of Egyptian mythology a force of creation (again related to dung) and rebirth and the God Kephri.
Spring plant buds. Or simply just spring air in a Regio at springtime.
A ray of sunshine - captured in a bottle, a mirror or a fragment of glass.
In continuation of the above suggestion from Bellysarius - a placenta. Even if eating placenta is a taboo -many animals do so and some older cultures did as well- it is a source of power of creation and of corpus. The same goes for natal water.
I could think of some holy vis versions of Creo - I somehow see the Divine as a typical creo source - but I do not expect your magi to want to reap divine vis... 
Hmmmm. And what would this regio entail? Some fawns cavorting, who don't like their mating rituals disturbed by roving magi? Put this together with some of the fertility magic from prior posts....
Perhaps the air is so fragrant with pleasing smells that it causes the grogs to want to join the cavorting fawns.
Is this a solo quest , or are other magi involved?
Would he need to do a deal with House Mercere , if he cannot find enough vis in time.
Alternatively , if he finds other vis , will he have to trade to get what he needs.
Possibly a Redcap knows of an unclaimed vis source and would ask for help to claim it.
Covenants , lists 03 Creo sources on page 72 , Corpus on page 78.
Fetish figurines each contain 01 pawn of Creo vis (page 55 , AM).
page 60 :
If the player finds such figurines , and destroys them to extract the vis ,
will he gain the enmity of a Cult that had hoped to study them?
(and would have traded favourably to do so)
Perhaps the Birthing Chamber in a cave system could lead to a regio.
The particular regio can only be entered by pregnant females , human or animal ,
or by anyone seeking to cure infertility.
(staying in the regio to harvest vis may negate a Longevity Ritual)
House Bjornaer might be interested in an area that Mythic Animals or Animal Spirits (non-Fae) frequent.
(again , the possibility of gaining enmity from the House if the area is defiled or tampered with)
Are you using Mystery Cults in your game?
Would the player magus be suitable Cult material.
Perhaps there is some Infernal Creo or Corpus vis to be had , some or part of the 15 pawns needed.
The player undergoes Initiation to gain the virtue Cthonic Magic (pages 83 , 91 & 123 in RoP:TI).
The drawbacks in regard to agents of the Divine are also listed.
A mandrake can contain the whole 15 pawns of creo corpus that you need. It would be a story to get it though, since appart from discovering it, you need to deal with its protectors (usually fae, but they can be magical as well) and survive the PeMe effect to turn you mad that its wailing will cause.
Plan B would be the usual bossom that contains creo, the usual graves with corpus (zombi hunting!!) and the common spider web that gets built whatever the number of times you remove it. It would be funny to have to brew that lñongebvity potion with unsavory materials like the heads of dead people and their semen. LMAO 
Plan C would be to raid a covenant's stores or declare wizard's wars on a magus that is known to have large stores of these materials (and be weaker than your magus)
Try not to make this a repeating source if it is only a vis hunt. 15 pawns is likely to dry a magical site dead.
Cheers,
Xavi
An idea I like is having vis in the placenta of babies carried in a particular aura. Could be a combination of Creo and Corpus... Amounts in the area of the strength of the aura... If this aura was the site of the covenant, it might encourage the magi to have more families around (which often leads to stories...)
There have to be a million sources of Corpus and Creo vis!
Think not in terms of vis coming from human bodies, but vis from things that have a magical power over the body. Or creation, or generative powers, etc. This opens the world of healing herbs, healing springs, and all that.
The Shape and Material Table (ArM5, page 110) is a big list of substances and their magical associations; I plunder it for vis ideas all the time.
For Creo, any fertility symbol should do nicely. How about a maypole? Or eggs. (Redcap headline: Vis-hungry magi go on Easter egg hunt! Sorry, couldn't resist)
Mandrake is probably my favorite. and has already been mentioned.